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dest Rocks • Planet Parade 




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YOU HAVE lOO DAYS TO TRAVEL 

3,924 KM ON FOOT. 

BY THE WAY, YOU'RE IN ANTARCTICA. 



Alain Hubert did it in 99 days. He is not one to shy away from challenges. In fact, you might say he 
provokes them. In 1997-98, he traversed the entire continent of Antarctica on foot and skis with 
a powerkite. His list of accomplishments reads like a history book. Among others he was the first 
to climb the sheer wall of the Holtanna in Queen Maud Land, Antarctica. He's crossed Greenland 
on skis. He's been to the geographic North Pole and has attempted Everest five times without 
oxygen. If anybody embodies the perpetual quest for adventure, Alain Hubert is that man. 



mm>m._ 




ROLEX 



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=!ER II ARE TRADEMARKS 



MAY 2 4 



VOLUME 113 



NUMBER 4 



FEATURES 



34 EGYPT'S YOUNG AND RESTLESS 

Tlirough Islam and the Internet, 
a new generation seeks its fair share. 

MARY KNIGHT 




40 A BIRTHSTONE FOR EARTH 

The oldest terrestrial material is a crystal 
of zircon, the sometime diamond substitute 
that can be a geologist's best friend. 

EDMOND A. MATHEZ 




COVER STORY 

46 AUDUBON IN KENTUCKY 

The young painter and ornithophile 
conceived his life's work in a country so rich 
in birds that their flocks blackened the sky. 

WILLIAM SOUDER 



ON THE cover: John James Audubon, 
Roseate Spoonbill (Engraving and 
color print by Robert Havell), 1836 




Visit our Web site at 
www.naturalhistorymag.com 



DEPARTMENTS 




4 THE NATURAL MOMENT 
Bloom On 

Photograpli by Andrew Davoll 

6 UP FRONT 

Editor's Notebook 

8 CONTRIBUTORS 

9 LETTERS 

12 SAMPLINGS 

News from Nature 

16 UNIVERSE 

The Planet Parade 
Neil deGrasse Tyson 

21 FINDINGS 

Of Mice, Men, and Genes 
Robert M. Sapolsky 

32 BIOMECHANICS 

How a Star Avoids the Limelight 
Adam Summers 




^ '^^^ 







53 REVIEW 

Brains and the Beast 
Frnns B.M. de Waal 

58 BOOKSHELF 

Laurence A. Marscliall 

63 nature.net 

Moving Mountains 
Robert Anderson 

64 OUT THERE 

Too Many X Rays 
Charles Lin 

65 THE SKY IN MAY 

Joe Rao 

68 AT THE MUSEUM 

72 ENDPAPER 

The Face of Extinction 
Hanna Rose Shell 



CREDITS: Page 8 




It's a Merchant ~ Ivory film on mopeds. 



Beyond the ISlh century fortress. Through cobblestone streets. Past Parliament and manicured lawns. Lie pink sand, 

royal palms, and untamed beaches. Sip high lea or knock hack a rum swizzle. Dive into blue-green ivaters. And a history 

steeped in civility- Two hours from the East Coast and Just this side of across the pond. 



1 .800. bermuda x 153 ~ www.bermudatourisin.coni 



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THE NATURAL MOMENT 



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For a drought-ridden conrinent 
patched over with poor soil, 
Australia has a remarkable variety 
of flowering plants. Tough, re- 
silient stalks, bedded in gravel and 
inured to the arid climate, repeat- 
edly bear exotic blossoms, such as 
the yellow flowers of Acacia glaii- 
coptem, or flat wattle, pictured here. 
Acacias are some of Australia's 
hardiest plants. More than 900 dif- 
ferent species have evolved there, 
colonizing even the inost desolate 
regions of the country. 

Flat watde has found its niche 
in a southwest pocket of the state 
of Western Australia. Each year, 
around the tiine Aussies celebrate 
their colorflil acacias on National 
Watde Day (September 1), pho- 
tographer Andrew Davoll visits 
four A. glaticoptem bushes in John 
Forrest National Park, sixteen 
miles east of Perth. He is drawn 
to their spring colors, but above all, 
he likes to photograph the flowers. 

The golden spheres seen here 
projecting at ninety-degree angles 
from the stem are made up of 
small, individual flowers. When 
one of the small flowers is polli- 
nated and fertilized, it goes to seed 
and snakes outward in a fuchsia- 
colored curlicue. After five years 
of tenaciously returning to the 
same spot, Davoll finally saw the 
arrangement he had been hoping 
for: a fiilly intact sphere of flowers 
(upper left) alongside balding 
flower heads and seedpods, all the 
stages of bloom, decUne, and birth 
on a single stem. 

— Erin Espelie 



6 NATURAL HISTORY May 2004 



UP FRONT 



Reality Check 



A couple of months ago, my friend Mary Knight, a visiting 
scholar at New York University and a consulting member of 
our staff, made a return trip to Cairo, Egypt, a city where 
she has lived on and ofl" since 1994. What originally drew her to the 
Middle East was a scholarly interest in ancient Egypt, but while there 
she played an active role in Egyptian intellectual life. Since her first 
arrival in Egypt, of course. Western attention to the Arab world has 
lurched from casual neglect to riveted, hysterical dismay — with few 
stops for cool dialogue in between. 

Knight made her return visit, in part, to give us all a reality check 
(see "Egypt's Young and Restless," page 34). She visited elementary 
schools, cafes, universities, research laboratories, and friends in low and 
in high places. Guiding her inquiries were the big, central questions 
about Egyptian society: What is it like nowadays to grow up among the 
wave of young adults who make up the elusive "Arab street"? Can 
young men find gainfiol, challenging employment? Do women have ac- 
cess to education, or do traditional values still block their way to eco- 
nomic independence? To what extent are hberalizing forces taking 
hold — forces such as education, scientific research, and competitive free 
markets? What drives some young people to embrace militant Islam? 
Knight brought along her camera as well as her notebook, and our 
pictures of Egyptian Ufe, by her and others, depict neither the rosy opti- 
mism of a society with a bead on its future, nor the grim, authoritarian 
fanaticism of a populace determined to reject liberal. Western values. 



Twenty-first-century Cairo may look like the neighborhood 
right around the corner, compared with the exotic world of the 
western Appalachians in eaiiy-nineteenth-century America. As a 
young man, the future artist and ardent bird naturalist John James 
Audubon took his family to what is now western Kentucky (see 
"Audubon in Kentucky," by William Souder, page 46). Now, 200 
years later, I walk in the woods whenever I can, and I know there are 
stiU plenty of places to find solitude and serenity out-of-doors. But 
Souder's account of the Kentucky wilderness, based on Audubon's 
acute observations, takes my breath away. The primeval abundance of 
the country must have seemed bottomless. The dimensions of Amer- 
ican nature seem sheer Paul Bunyan, until a sober observer such as 
Audubon assures you it really did take three days for a single flock of 
passenger pigeons to fly past. That world is truly gone. 



We are delighted to announce that Natural History has been 
nominated for a National Magazine Award for Essays, for 
Robert M. Sapolsky's "Findings" column, "The Pleasure (and Pain) 
of 'Maybe'" (September 2003). The award is the most prestigious 
prize in magazine journalism; the winner will be announced on 
May 5. Sapolsky's latest essay, "Of Mice, Men, and Genes," appears 
on page 21. Congratulations, Robert! — Peter Brown 



ANTARCTICA 

ExpCriGnCG IVl9tlCirSBThere is no avoiding the word extrenne. Antarctica 
spawns icebergs the size of Rhode Island. Its winds are at times fierce and unpredictable. Its 
surrounding waters not well charted. Nowhere on earth is adventure greater and nowhere are 
mistakes more costly. Our hard-won experience, dating back to 1966, gives us the confidence 
to explore, to test limits and even kayak among giant icebergs. Our captains and expedition 
leaders have hundreds of Antarctic expeditions to their credit. They might even guide you to 
one of Antarctica's most spectacular coves, named after my father. It's a bold, magnificent 
decision to explore Antarctica. If you make that 
decision, do go with us. Nowhere on earth will 
experience matter more. 




Sven/Olof Lindblad 



Lindblad Cove 63°51'S, 59°27'W 
Cove, 5 km wide, between Almond Point and 
Auster Point in Ctiarcot Bay, TrinityPeninsula. 
Named by US-ACAN in 1995 in commemora- 
tion of Lars-Eric Lindblad (1927-94), pioneer 
in Antarctic tourism. A noted conservationist, 
Mr. Lindblad operated the first cruise to 
Antarctica in 1966 and was a leader in the 
concept of expedition tourism as a 
means of environmental awareness. 

July 12, 1996, U.S. Board (g_ 
on Geographic Names 




1-800-EXPEDITION 

expeditions.com/nh 

or see your travel agent 



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CONTRIBUTORS 

After traveling to southern Australia each austral spring for 
five years to photograph the same cluster of acacia bushes, 
Andrew Davoll ("The Natural Moment," page 4) hit the 
jackpot in his attempt to capture a stalk with both its flowers 
and its seedpods on display. A native of Great Britain, Davoll 
now lives and works in Perth, and specializes in photograph- 
ing the rich flora of western Australia. When he is not plying 
his trade, he enjoys long-distance ocean swimming and marathon running. 

Mary Knight's interest in the lives of contemporary Egyp- 
tians ("Egypt's Young and Restless," page 34) was sparked 
during her tenure as a Fulbright scholar in 1994—95, studying 
the geography of ancient Egypt at 'Ain Shams University in 
Cairo. While pursuing that research, she also completed a 
study of the practice of female genital mutilation in antiquity, 
a project that led to discussions with modern Egyptians on 
how the practice is viewed today. Knight is a visitmg scholar at New York Uni- 
versity, and is co-editing a book on nudity in the ancient Mediterranean world. 

A geologist and curator in the Department of Earth and Planetary Sciences 
at the American Museum of Natural History in New York City, Edmond 
A. Mathez ("A Birthstone for Earth," page 40) is an expert in the geo- 
chemistry of the volatile elements. His research interests in- 
clude the solidification of large magma bodies, the electri- 
cal properties of rocks, and the early Earth. He was one of 
the team who recovered the underwater hydrothermal 
vents known as black smokers, which support sulfur-loving 
life-forms m the deep ocean, and which may resemble the 
structures that nurtured the first life on the planet. With his 
museum colleague James D. Webster, he co-authored The 
Earth Machine: The Science of a Dynamic Planet, forthcoming this month from 
Columbia University Press. 

Minnesota-based journaHst William Souder ("Audubon in 
Kentucky," page 46) takes his inspiration from the living 
world. For his first book, A Plague of Frogs, Souder spent 
several years slogging through swamps and sitting through 
contentious scientific meetings to chronicle the environmen- 
tal threat posed by crashes of amphibian populations. For 
his new book, about John James Audubon, he explored the 
quieter (and drier) confines of library archives in the United 
States and abroad, poring over the letters and journals of one of America's 
greatest ornithologists. Having written about both frogs and birds, Souder says 
the ocean may be the subject of his next book. 





CREDITS Cover: ©Acidcmy of Natural Sciences of Philadclpliu/CORBIS: p. 4-5: Andrew DavoU/Lochman Transparencic!; p.lO: 
©Bud Grace: p.l2(top): ©John Cancalosi/Vireo; p.]2(botcom); J.R Sniol; p.l4(cop): ©Marc Cliamberlaiii/SeaPics.coni: p.H(bottom}: 
Shane Eriio/NSERC: p.l5(left): ©D. van Ravenswaay/Photo Researcliers. Inc.: p.l5(righc): ©James C, Liao. Harvard University'; 
p.l5(bottoni) a.c.d: Frans Lancing/Mniden Pictures; b: Gerry EUis/iVluiden Pictures; pp.l6-I7 (from top Ieft:(# 1. 3. 5) and p. 20 {#1, 
3): Scala/Art Rcsourcc.NY: p.l6 (#2): USGS/Photo Researchers, Inc.; (#4): NASA/Science Source/Photo Researchers, Inc.: (#6): 
David Crist and the WFPC2 Science Team SPL/NASA; p.2i:i (#2): NASA/JPL/University of Arizona; p.20: Reta Beebe (New IVlcx- 
ico State University), D. Gihiiorc, L. Bergeron/STScI/NASA; p.21: ©Frederick Warne & Co., 1904. 2002; p.24; Private CoUec- 
tion/Bridegman Art Ubrary; pp.34 and 39: Abbas/Magnum Photos; p.35 (top & bottom), pp.37 and 38: ©Mary Knight: p.36: Ed 
Kashi/IPN/ Aurora Photos; p. 40 (left): Harold and Erica van Pclt/AMNH; p.40-41 ; ©James L, Amos/CORBIS; p.42 & 43 iUustradons 
by Patricia J. Wynne; p. 44: ©Martin J. Whitehouse, Swedish Museum of Natural History: p,45: ©Minik Rosing, Geologisk Museum 
Copenhagen; pp.47. 48, 51. and 52: The Granger Collection, NY; p,53 and p,56; courtesy Barbara Gladstone Gallery NY; p.58: 
©Stephen Dalton/Photo Researchers. Inc.; p. 59: Bonhanis, London/Bridgeman Art Library; p.62: ©E Gilson/Peter Arnold; p.64: 
©David A. Aguilar, Harvard/Smithsonian Center for Astrophysics; p. 65: Fanny Breiman, Gikv)', 1997, Estate of Fanny Brennan. cour- 
tesy Salander O'Reilly Galleries. NY; p. 72: ©Smithsonian Photographic Services. 



mm 



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8 NATURAL HISTORY May 2004 



LETTERS 



Browbeaten Ancestors 

In "Headstrong 
Hominids" (2/04), Noel 
T. Boaz and Russell L. 
Ciochon propose that the 
prominent brow ridges of 
Homo erectiis crania evolved 
to protect our contentious 
large male ancestors who 
were clubbing each other 
during combat. But large 
male gorillas also have 
heavy brow ridges, and 
they rarely (if ever) use 
clubs when altercations 
arise among them. Could 
large brow ridges have first 
evolved to protect large 
arboreal primates from 
damaging their brains by 
accidentally banging their 
heads while rapidly climb- 
ing trees? 
Juliati Kane 
Great Neck, New York 



Noel Boaz and Russell 
Ciochon give a number 
of possible explanations 
for male-male violence — 
individual or group con- 
flict resolution, competi- 
tion for mates, competi- 
tion for dominance, and 
so on. Yet they cite a 
study of Australian 
Aboriginal skulls that 
found healed fractures in 
"59 percent of the female 
crania and in 37 percent 
of male crania." If more 
women than men were 
getting their heads bashed 
in, doesn't this suggest 
that men were beating up 
women — what we cur- 
rently refer to as "domes- 
tic violence"? 
Henya Rachmiel 
Commerce Township, 
Michigan 



I read "Headstrong 
Hominids" with a profes- 
sional curiosity, because I 
work with the traumatically 
brain-injured. Whereas H. 
erectm\ injuries were in- 
flicted by other club-wield- 
ing protagonists, my clients 
bear the scars mostly of 
vehicular accidents. They 
owe their survival to the 
evolution of a thick, bony 
mass that shielded the inner 
cortex. I wonder if we will 
evolve harder heads, better 
suited for modern trafluc 
conditions. 
Arnold SoUnsky 
Long Island Head Injury 
Association 
Comniack, New York 

Noel T. Boaz and Russell 
L. Ciochon reply: Julian 
Kane points out apparent 



similarities between gorilla 
and H. erectus brow ridges. 
Protection of the eye is 
certainly an important fianc- 
tion of the brow ridge, but 
we would ascribe its extra 
robustness in gorillas and 
H. erectus to different causes. 
The gorilla's brow ridge is a 
bony response to chewing 
forces transmitted up to the 
(thin-walled) skuU fi^om a 
large face that supports huge 
canine teeth. H. erectus has a 
reduced face and relatively 
small teeth but a massive 
brow ridge connecting back 
to a thick skuU. 

Henya Rachmiel's ques- 
tion brings up an intriguing 
impHcation of our hypothe- 
sis of cranial bone thickness: 
if women in general have 
thinner skulls than men, 
then they wiU be more 



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susceptible to cranial frac- 
ture when struck in the 
head. If we assume a 15 to 
20 percent size difference 
between the sexes for H. 
erect Hs (about twice the 
difference between modern 
human males and females), 
it is likely that H. crectiis 
males could have disabled or 
killed females more readily 
than they could other 
males. On the other hand, 
one cannot assume that 
males dealt all the fractures. 
The Australian ethno- 
graphic data indicate that 



More Trash Talk 
According to Charles 
Moore ("Trashed," 
11/03), gyres have pulled 
our oceangoing plastic 
detritus into localized 
concentrations. Is there 
any reason the nations of 
the world couldn't orga- 
nize a cleanup at appro- 
priate intervals? 
Stei'e E. Hartiuan 
Saco, Maine 

Charles Moore describes 
an appalling situation, but 
leaves some questions 




^-«'^\v-" 



sm 








'Call it ci'olittion if you want. I say the kid needs a haircut. " 



many of the cranial fractures 
in women resulted from dis- 
putes with other women. 
Arnold Solinsky notes 
that many cranial fractures 
result from motor vehicle 
accidents these days. H. 
erectus, with its thick skull, 
would undoubtedly have 
fared better in this regard. 
If the selective force of 
motor vehicle accidents 
remains the same for many 
thousands of years, skull 
thickness in Homo sapiens 
might increase as an evolu- 
tionary response, if not off- 
set by such disadvantageous 
effects as increased head 
weight, poor scalp circula- 
tion, and neck musculo- 
skeletal pain. 



unanswered. How does the 
plastic get into the ocean? 
How fast is it building up? 
And what is being done — 
or what should be done — 
about it? 
Guy Otteti'ell 
Lyme Regis, England 

I understand that some 
bacteria aid in cleaning up 
oceanic oil spiUs. Is there 
any such organism that can 
break down these oil-based 
pollutants? 
Allan J. Sander 
Trabuco Canyon, California 

Charles Mooi\£ implies: 
Efforts are under way to 
accomplish something Hke 
what Steve E. Hartman en- 



visions, principally as a way 
to protect the critically en- 
dangered Hawaiian monk 
seal from entanglement in 
derelict fishing nets. 

Unfortunately, I do not 
believe this action will 
stop the buildup of plastic 
particulates, the photo- 
degraded bits of plastic 
trash that now outweigh 
plankton in much of the 
ocean. Plastic particles, 
which are nearly the same 
density as seawater, are 
mixed into the entire 
ocean. No cleanup of the 
1.37 billion cubic kilome- 
ters of seawater is possible. 
The only cleanup possible 
is to attack the problem at 
its source. 

In reply to Guy 
Ottewell, the farther you 
get from civilization, the 
more closely associated 
plastic debris in the ocean 
is with the fishing industry. 
But 80 percent of the total 
debris comes firom land- 
based sources, not all of 
them near the coast (much 
is carried to the ocean 
from far inland, by rivers) . 
The plastic industry itself 
accounts for millions of 
preproduction plastic pel- 
lets, as well as much plastic 
dust and sawdust from 
transfer, molding, and re- 
cycling operations — small 
bits less than five millime- 
ters across that are hard to 
control. During the 1990s, 
Haruo Ogi of Hokkaido 
University found a tenfold 
increase of plastic particles 
in his trawls off Japan. 

Currently the gyre has 
an average of one particle 
per square meter in areas of 
high concentration. In 
windblown collections of 
debris, the surface is more 
than covered. Plastics need 



to be designed for recy- 
cling, and those who make 
them should be prepared to 
take on that responsibility. 

In response to Allan J. 
Sander, I know of no 
bacteria that eat consumer 
plastics, but, in any case, 
toxic chemicals are too 
dispersed in the ocean to 
be addressed by the tech- 
niques that are used in 
concentrated spills. 

To Persist in Error . . . 
I, too, noticed the substi- 
tution of Cape Horn for 
the Cape of Good Hope 
in Adam Summers's 
"Biomechanics" column 
("Like Water Off a Beetle's 
Back," 2/04), and cor- 
rectly guessed that people 
would write in to point it 
out. But I believe that 
your published correction 
("Amendment," 3/04) is 
not quite right either. 

It is true that the Cape 
of Good Hope is the 
"milestone" you have to 
get past in saiHng between 
the Atlantic and Indian 
Oceans, in terms of 
currents, weather, and its 
prominence as a geo- 
graphical feature. But it is 
not, as you have it, "the 
southern tip of Africa." 
That, I believe, is Cape 
Agulhas, off to the east a 
bit and something like half 
a degree farther south. 

(I must admit I was 
encouraged to write this 
note after reading Peter 
Brown's excellent editorial 
on fact-checking in the 
same issue.) 
Eric Wolman 
Potomac, Maryland 

Natural History k e-mail 
address is nhnnag@natural 
historymag.com 



10 I NATURAL HISTORY May 2004 



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SAMPLINGS 



Cozy 1 BR, Forest Vu 

Come springtime, birds everywhere 
are busy nesting and reproducing. 
But not every bird gets to breed — 




Male common starling 
in breeding plumage 

before you can raise a family you 
usually need a place to call home, 
and young adults are often edged 
out of the housing market. Those 
birds become floaters, sitting out 
the breeding season and presum- 
ably moping. A recent study, how- 
ever, suggests nonbreeders make 
the best of a bad situation. 

Michael Tobler and Henrik G. 
Smith, both animal ecologists at 
Lund University in Sweden, watched 



common starlings and their atten- 
dant floaters throughout the star- 
lings' breeding season, in May. The 
two investigators found that male 
floaters stay within specific areas, 
covering about one square mile, 
and often visit the nesting cavities 
(tree holes) used by the breeders, 
particularly when the young are still 
inside. Apparently the floaters are 
checking out real estate that may 
become available the following year. 

Tobler and Smith also set up 
empty, nestworthy boxes in the fall, 
before the starlings migrated, so that 
the birds could visit them; the follow- 
ing spring those boxes were occu- 
pied. Other, equivalent boxes were 
installed in winter, when the starlings 
were gone. Yet despite the housing 
shortage, most of the unexplored 
boxes remained empty the following 
spring. Evidently the birds prefer ad- 
vance planning. ("Specific floater 
home ranges and prospective behav- 
iour in the European starling, Sturnus 
vulgaris," Naturwissenschaften 
91:85-89, February 2004) 

— Stephan Reebs 



Like Mother, Like Son 

Thirty years ago Robert L. Trivers, an evolutionary 
biologist , and Dan E. Willard, a mathematician, 
formulated a sage hypothesis: if strong, healthy 
mothers tend to bear strong sons, and if those 
sons monopolize matings and tend to produce 
more young than strong daughters would, then 
stronger mothers should give birth to more male 
than female offspring. The hypothesis has proved 
true for certain insects and birds, but the verdict 
for mammals has been equivocal. 

Now two zoologists, Ben C. Sheldon of the 
University of Oxford and Stuart A. West of the 
University of Edinburgh, have shown that the hy- 
pothesis holds for a large group of mammals: the 
ungulates (hoofed creatures such as deer and 
pigs). They also found that a mother's overall 
condition before conception can play a role in pro- 
ducing sons, but that the mother's social standing 
has a greater impact than do purely physical fac- 
tors such as body weight. Motherhood is future- 
oriented, they argue, and social dominance is 
probably the better long-term indicator of a 
female's access to resources. The effect is mild, 
but dominant females do give birth to sons slightly 
more often than to daughters. ("Maternal domi- 
nance, maternal condition, and offspring sex ratio 
in ungulate mammals," American Naturalist 
163:40-54, January 2004) —S.R. 



AFTERMATH OF OCCUPATION 



Scattered across the Canadian High 
Arctic are the remains of small groups 
of dwellings, sunken partway into the 
ground and built out of whale bones. 
Nearby, generally, stands a freshwater 
pond, along with piles of decomposing 
bones from whales and other animals 
hunted by the residents. The sites are 
the abandoned villages of Thule Inuit 
whalers who emigrated from Alaska 
about a thousand years ago, and 
whose presence, activity, and refuse 
left an enduring mark in the region 
well before the arrival of Europeans. 

Marianne S.V. Douglas, a paleoecologist 
at the University of Toronto, and a team of 
colleagues studied sediments from a quarter- 
mile-long pond in one Thule village, inhabited 




Thule Inuit dwelling (reconstructed) in Canada's High 
Arctic. The whale-bone roof frame would originally 
have been covered with skins and sod. 



from the early thirteenth century through the 
end of the sixteenth. They discovered that 
during the whalers' occupation, moss and an 
associated diatom proliferated, replacing the 



bottom-dwelling diatom Fragilaha pinnata 
as the pond's dominant flora. 

Douglas and her associates also 
found concentrations of nitrogen-1 5, 
an isotope characteristic of marine life, 
to be higher than in similar ponds. The 
investigators thus think nutrients from 
the processed whale carcasses must 
have fertilized the pond. Even today, 
as lingering whale bones continue to 
leach phosphorus into the pond, its 
chemistry remains quite different from 
that of ponds not situated near his- 
torical settlements. ("Prehistoric Inuit 
whalers affected Arctic freshwater eco- 
systems," Proceedings of the National 
Academy of Sciences 101:1613-17, 
Februar/10, 2004) —S.R. 



12 NATURAL HISTORY M3y 200A 





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SAMPLINGS 



Because one kind of prion causes "mad 
cow disease," prions in general get a lot of 
bad press. The very word "prion" may con- 
jure horrific visions of saboteurs cascading 
through brain tissue. But not all prions are 
deadly. Kausik Si, a neurobiologist at 
Columbia University, and his colleagues 
propose that at least one protein that acts 
like a prion may do something positive: it 
may help store long-term memories in the 
sea hare, Aplysia, a marine invertebrate 
favored in neurological research because 
of its large neurons. 

Memories seem to form when two stimu- 
lated neurons change the way they commu- 
nicate across a synapse, the gap between 
them. The prion-like protein in Aplysia re- 
sides in the synapse. Si and his colleagues 



Prions Make Amends 

speculate that when the neurons 
are stimulated, the protein re- 
folds itself and causes other, 
neighboring proteins of the 
same kind to follow suit — much 
like the self-perpetuating pnons 
of ill repute. 

Instead of wreaking havoc, 
however, the "domino effect" 
ends up strengthening the 
synaptic connection. The shape 
change in the prion-like pro- 
teins leads to the synthesis of 
other kinds of proteins that 
help stabilize the connection. The net ef- 
fect is that Aplysia's neurons retain memo- 
ries for several days instead of just a few 
minutes. ("A neuronal isoform of CPEB 




Invertebrates have memories too. 



regulates local protein synthesis and stabi- 
lizes synapse-specific long-term facilitation 
in Aplysia," Ce/1 115:893-904, December 
26, 2003) —Caitlin E. Cox 



ROLE REVERSAL 

MAN BITES dog; FROG FENDS OFF LION; PLANET HEATS STAR: silly 

headlines from the tabloids, right? But stow your skepti- 
cism about that last story: planets aren't always passive re- 
cipients of heat and light. Evgenya Shkolnik, an astronomer 




Orbiting planet causes moving hot spot on host star 

at the University of British Columbia in Vancouver, and her 
colleagues have spotted a feisty, Jupiter-size planet some 
ninety light-years from Earth whose strong magnetic field 
and close-in orbit excites a hot spot on the surface of its 
host star. As the planet whizzes around the star, the hot 
spot faithfully tracks its orbit. ("Evidence for planet- 
induced chromo&pheric activity on HD 179949," Astro- 
physicalJournal 597:'! 092-96, November 10, 2003) 

— Joomi Kim 



Seeing Red 



Stroll into a pet shop, and you'll 
find a host of colorful cages 
and toys for the rodent in your 
life. The colors, of course, are 
designed to appeal to (human) 
buyers, but it turns out that col- 
ors affect the animals as well. A 
recent study by Chris M. Sher- 
win and Elizabeth F. Glen, both 
behavioral biologists at the Uni- 
versity of Bristol in England, 
suggests that mice are discom- 
bobulated by red. 

Sherwin and Glen raised mice 
in "home cages" painted black, 
white, red, or green. Then they 
placed the mice in two test envi- 
ronments, each with a choice of 
places to go, and clocked the 
time the mice spent in each 
place. In one environment, the 
mice could enter one of four 
"preference cages," each 
painted the color of one of the 
home cages. In the second envi- 
ronment, a standard test of anxi- 
ety levels, they could enter ei- 



ther the walled or the wide-open 
arms of a cross-shaped maze. 

Results: no matter which 
color their home cages had 
been painted, the animals spent 
the least time in the red prefer- 
ence cage. And the animals 
raised in red home cages spent 
the least amount of time in the 
open, unprotected arms of the 
maze. Conclusion: red makes 
mice nervous. 

You probably wouldn't feel 
too happy in a living room with 
bright red walls, but Sherwin 
and Glen are surprised that 
mice have a similar reaction. 
One possible trigger for the 
mice's distress is that red is 
often displayed on the body of 
toxic species, as a warning to 
leave them alone. ("Cage 
colour preferences and effects 
of home cage colour on anxiety 
in laboratory mice," Animal 
Behaviour 66: 1085-92, Decem- 
ber 2003) —S.R. 



14 NATURAL HISTORY May 200'' 



EVIDENCE OF IMPACT 



Few scientists will disagree if you say that 
65 million years ago, something killed off 
a large fraction of Earth's inhabitants — 
including those most spectacular of crea- 
tures, the dinosaurs. But nowadays, if you 
contend that the ultimate killer was the 
huge meteorite whose impact created the 
even huger Chicxulub crater, centered on 
Mexico's Yucatan Peninsula, some earth 
scientists will tell you you're wrong. 

Since the early 1990s, it has been 
widely accepted that the Chicxulub 
crater was formed 65 million years ago, a 
date that coincides with the mass extinc- 




Chicxu/ub crater (circle), excavated 65 m/Hion — or 
more? — ^years ago by a massive meteorite impact 
centered on Mexico's Yucatan Peninsula 

tions at the end of the Cretaceous pe- 
riod, often called the K/T boundary. To 
put that date to the test, a rock core 
measuring 4,950 vertical feet — dubbed 
the Yaxcopoil-1 core — was recently 
extracted from beneath the floor of the 
crater so that geologists could examine 
the stratigraphic evidence. Fair enough. 



Trouble is, according to Gerta Keller, 
a geologist at Princeton University, and 
her colleagues, the core suggests the 
Chicxulub crater predates the K/T 
boundary by 300,000 years. 

The geologists base their view on 
several factors. For example, glass formed 
during the impact occurs lower — that is, 
about 300,000 years earlier — in the core 
than does the familiar green clay that 
marks the K/T boundary worldwide. 
Additional signs that the impact predates 
the K/T boundary are embedded in rock 
layers all over northeastern Mexico. 

What's more, Keller says, there's ample 
evidence that by the time the K/T 
extinctions took place, the Earth's flora 
and fauna were already struggling. 
Volcanic eruptions were probably ex- 
tensive and greenhouse warming se- 
vere, and the biota may also have been 
exposed to a number of devastating 
meteorite impacts. 

Not everyone is convinced by the 
new analysis. In spite of live and online 
debates, Jan Smit, for instance, a geol- 
ogist at the Free University Amsterdam 
and an original proponent of the con- 
nection between Chicxulub and the 
K/T mass extinctions, remains uncon- 
vinced. A single impact, he says, explains 
all the known data. ("Chicxulub impact 
predates the K-T boundary mass extinc- 
tion," Proceedings of the National 
Academy of Sciences 101:3753-58, March 
16, 2004; www.geolsoc.org.uk/template. 
cfm?name=NSG2349857238495) 

— Jordan Paul Amadio 



Cryptic Creatures 




Only three of these pictures are close-ups of the same animal. Which one doesn't belong? 

(Answer on page 31) 



Different Stroke 

In turbulent waters, fish tend to "go 
with the flow." They save energy by 
slaloming back and forth between the 
vortices, or whirlpools. Now biolo- 




Rainfaow trout surfing 
whirlpools 

gists have determined that when 
they slalom, fish adopt a previously 
unknown swimming style that enables 
them to maneuver more effectively. 

James C. Liao, a biologist at 
Harvard University, and his col- 
leagues made high-speed movies of 
rainbow trout swimming side-to-side 
in a pattern they call the "Karman 
gait" (for the daddy of aerodynamics, 
Theodore von Karman). The pattern, 
adopted by the fish in an agitated 
stream or within a fish school, calls 
on fewer muscles than does the un- 
dulatory swimming pattern the fish 
use in smooth-flowing water. Only 
certain muscles near the head are 
activated. The body flutters gently, 
like a flag flapping in the breeze, 
relaxed and ready to catch a boost 
from passing vortices. 

Liao and his colleagues may have 
big fish to fry when it comes to 
applications of their work. Unmanned 
submarines, for instance, could 
reduce energy costs by traveling in 
a Karman gait. And the new under- 
standing might help engineers 
design innovative passageways to 
help migrating fish bypass dams. 
("Fish exploiting vortices decrease 
muscle activity," Science 302:1566-69, 
November 28, 2003) — J. PA. 



May 2004 N.\TUR.M HISTORY 15 



UNIVERSE 



The Planet Parade 



For millennia, planets were just mysterious, wandering points 
of light in the night sky. Now they are destinations. 



In the study of the cos- 
mos, its hard to come 
up with a better tale 
than the centuries-long 
history of attempts to un- 
derstand the planets — 
those sky wanderers that 
make their rounds against 
the backdrop of stars. Of the 
eight objects in our solar system that 
are indisputably planets, five are read- 
ily visible to the unaided eye and were 
known to the ancients, as well as to 
observant troglodytes. Each of the 
five — Mercury, Venus, Mars, Jupiter, 
and Saturn — was endowed with the 
personality of the god for which it 
was named. Mercury, which moves 
the fastest against the background 
stars, was named for the Roman mes- 
senger god — the fellow usually de- 
picted with sniall and aerodynami- 
cally useless wings on his heels or his 
hat. Mars, the only one of the classic 
wanderers (the Greek word plauete 
means "wanderer") with a reddish 
hue, was named for the Roman god 
of war and bloodshed. Earth, of 
course, is also visible to the unaided 
eye. Just look down. But terra firma 
was not identified as one of the gang 
of planets until after 1543, when 
Nicolaus Copernicus advanced his 
Sun-centered model of the universe. 
To the telescopically challenged. 

The images on tin's and the opposite page are 
Roman gods as depicted by the Italian Renais- 
sance painter Pietrc Perugino, paired with 
photographs of the planets named after them. 
Left to right: Mercury, Venus, and Mars. 




the planets were, and 
are, just points of light 
in the sky that happen 
to move. Not until 
the seventeenth cen- 
tury, with the prolif- 
eration of telescopes, 
did astronomers discover 
that planets are orbs. Not 
until the twentieth century were 
the planets scrutinized at close range, 
with space probes. And 
not until later in the 
present century arc 
people likely to 
visit them. » 



H 



umanity 
had its first 




looking 



telescopic en- '^, 
counter with the 
celestial wanderers 
during the winter of 
1609-10, when Galileo 
through an excellent telescope of his 
own design and manufacture, saw the 
planets as spheres — perhaps even other 
worlds. One of them, brilliant Venus, 
went through phases just like the 
Moon's: crescent Venus, gibbous 
Venus, full Venus. Another planet, 
Jupiter, had moons all its own, and 
Galileo discovered the four largest: 
Ganymede, Callisto, lo, and Europa, 
all named for assorted characters in 
the life and times of Jupiter's Greek 
counterpart, Zeus. 

The simplest way to explain the 
phases of Venus, as well as other fea- 
tures of the planet's motion against the 



By Neil deGrasse Tyson 



sky, was to assert that the planets re- 
volve around the Sun, not the Earth. 
Indeed, Galileo's observations strongly 
supported the universe as envisioned 
and theorized by Copernicus. 

Jupiter's moons took the Coperni- 
can universe a step further: though Ga- 
lileo's twenty-power telescope could 
not resolve the moons into anything 
larger than pinpoints of light, no one 
had ever seen a celestial object revolve 
around anything other the Earth. It 
was an honest, simple observation 
of the cosmos, but the Roman 
Catholic Church and "common 
sense" would have none of it. 
With the aid of his telescope, 
GaUleo discovered a contradic- 
tion to the dogma that Earth oc- 
cupied the central position in the 
cosmos — the spot around which 
all objects revolve. In early 1610, in 
a short but seminal work he titled 
Sidereus Niiiicitis (Starry Messenger), 
Galileo reported his persuasive findings. 



o 



nee 
Coper- 




nican model 
had become 
widely ac- 
cepted, the 
arrangement 
of the heav- 
ens could legit- 
imately be called 
a solar system, and Earth 
could take its proper place as one 
among six known planets. Nobody 
imagined there could be more than 



16 NATURAL HISTORY May 2004 



SLx. Not even the English astronomer 
Sir William Herschel, who discovered 
a seventh in 1781. 

Actually, the credit for the first 
recorded sighting of the seventh planet 
goes to the EngUsh astronomer John 
Flamsteed. But in 1690, when Flam- 
steed noted the object, he didn't see it 
move. He assumed it was just another 
star in the sky, and named it 34 Tauri. 
When Herschel saw Flamsteed's "star" 
drift against the background stars, he 
announced — operating under the un- 
witting assumption that planets were 
not on the Hst of things one might dis- 
cover — that he had discovered a 
comet. Herschel planned to call the 
newfound object Georgium Sidus 
("Star of George"), after his benefac- 
tor. King George III of England. If the 
astronomical community had re- 
spected Herschel's wishes, the roster of 
our solar system would now include 
Mercury, Venus, Earth, Mars, Jupiter, 
Saturn, and George. In a blow to 
sycophancy, however, the object was 
ultimately called Uranus, in keeping 
with its classically named brethren — 
though some French and American 
astronomers kept calling it "Her- 
schel's planet" until 1850, just several 
years after the eighth planet, Neptune, 
was discovered [see "Jlie Rise and Fall 
of Planet X," by Neil deGrasse Tyson, 
June 2003]. 

Over time, tele- 
scopes kept get- 
ting bigger and 
sharper, but the 
planetary de- 
tails astrono- 
mers could dis- 
cern did not 
much improve. 
Because every tele- 
scope, no inatter the size, 
viewed the planets through Earth's tur- 
bulent atmosphere, the best pictures 
were still a bit fuzzy. Nevertheless, in- 
trepid observers managed to discover 
features such as Jupiter's Great Red 
Spot, Saturn's rings, Mars's polar ice 
caps, and dozens of planetary moons. 
Human knowledge of the planets was 
still meager, though, and where igno- 




rance lurks, so too do the frontiers of 
discovery and imagination. 

Consider the case of Percival Low- 
ell, the highly imaginative and 
wealthy American businessman and 
astronomer, whose exploits took place 
at the end of the nineteenth century 
and the early years of the twentieth. 
Lowell's name is linked with the Low- 
ell Observatory in Flagstaff, Arizona, 
the "canals" of Mars, the "spokes" of 
Venus, and the search for Planet X. 
Like so many other astrophiles around 
the world, Lowell picked up on the 
proposition by the Italian astronomer 
Giovanni Schiaparelli that linear 
markings visible on the Martian sur- 
face were canali. 

The problem was that the word 
means "channels," but Lowell and many 
of his contemporaries chose to translate 
it as "canals," because the 
markings were thought 
to be similar in scale 
to major public- 
works projects 
under way on 0^' 
Earth. Lowell 
dedicated himself 
to the observarion 
and mapping of the 
Red Planet's network 
of waterways, surely (or 
so he fervently contended) constructed 
by technologically advanced Martians. 
He believed that the cities of Mars, 
having exhausted their local water 
supply, had had to dig canals to 
transport water fi^om the planet's 
polar ice caps to the more popu- 
ous, equatorial zones. 
Another object of Lowell's atten- 
tions was Venus, whose ever-present 
and highly reflective clouds make it one 
of the brightest objects in the sky. Venus 
orbits relatively near the Sun, and so as 
soon as the Sun sets — or just before the 
Sun rises — there's Venus, hanging glo- 
riously in the twilight. And because the 
twilight sky can be quite colorful, 
there's no end of 9-1-1 calls reporting a 
glowing, colorful UFO hovering on 
the horizon. 

Lowell maintained that Venus 





sported a network of massive, mosriy 
radial spokes — more canali — emanat- 
ing from a central hub. The spokes he 
saw remained a puzzle until quite re- 
cently, when a retired optometrist 
named Sherman Schultz, from Saint 
Paul, Minnesota, wrote a letter in re- 
sponse to an article on the spokes by 
William Slieehan and Thomas Dob- 
bins in the July 2002 issue of Sky and 
Telescope magazine. 

Schultz pointed 
out that the 
optical setup 
Lowell pre- 
ferred for 
viewing the 
Venutian sur- 
face was sim- 
ilar to the giz- 
mo used to exam- 
ine the interior of 
patients' eyes. After seeking a couple 
of second opinions, the article's au- 
thors established that what Lowell 
seemed to see on Venus was in- 
stead the network of shadows 
cast on Lowell's own retina by 
his own ocular blood vessels. 
When you compare Lowell's 
diagram of the spokes with a 
diagram of the eye, the two 

match up, canal for blood vessel. 
And when you combine the unfor- 
tunate fact that Lowell suffered from 
hypertension — which often shows 
up in the vessels of the eyeballs — with 
his will to beheve, it's no surprise that 
he had Venus as well as Mars teem- 
ing with intelligent, technologically 
capable inhabitants. 

Alas, Lowell fared only slightly bet- 
ter with his search for Planet X, a 
planet thought to He beyond Neptune. 
Planet X does not exist, as the astron- 
omer E. Myles Standish Jr. decisively 
demonstrated a decade ago. But Pluto, 
discovered at the Lowell Obser^'atory 
in February 1930, some thirteen years 
after Lowell's death, did serv-e as a tair 
approximation for a while. 

Within weeks of the obsei-\'ators''s 
big announcement, though, some 
astronomers had begun debating 
whether or not Pluto should be classi- 



M ay 2004 NATUR..\L HISTORY 17 



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fied as the ninth planet. Given the de- 
cision several years ago by my home in- 
stitution to represent Pluto as a comet 
rather than as a planet, I've been drawn 
into that debate myself, and I can assure 
you, it hasn't let up yet. Asteroid, plan- 
etoid, planetesimal, large planetesimal, 
icy planetesimal, minor planet, giant 
comet, Kuiper Belt object, trans-Nep- 
tunian object, methane snowball, 
Mickey Mouse's' dim-witted blood- 
hound — anything but number nine, 
we naysayers argue. Pluto is just too 
small, too lightweight, too icy, too ec- 
centric in its orbit, too weird. And by 
the way, we can say the same about 
the most recent high-profile contender 
for tenth place, the ruddy object 
Sedna, with which Pluto may have 
more in common than either object 
has with the planets in our solar system. 

Time and technology moved on. 
Come the 1950s, radio-wave 
observations and better photography 
began to bring fascinating facts about 
the planets to light. By the 1960s, 
people and robots had left Earth to 
take pictures of the planets. Each new 
fact and photograph lifted the curtain 
of ignorance a little bit higher. 

Venus, named after the goddess of 
beauty and love, turns out to have a 
thick, almost opaque atmosphere, 
made up mostly of carbon dioxide and 
bearing down at nearly a hundred 
times the sea-level pressure on Earth. 
Worse yet, the surface air temperature 
approaches 900 degrees Fahrenheit. 
On Venus you could cook a sixteen- 
inch pepperoni pizza in nine seconds, 
just by holding it in the air. (Yes, I did 
the math.) Such extreme conditions 
pose great challenges to space explo- 
ration, because practically anything 
you can imagine sending to Venus 
will, vi^ithin a moment or two, get 
crushed, melted, or vaporized. So 
you'd better be heatproof or just plain 
quick if you're collecting data from 
the surface of this forsaken place. 

It's no accident, by the way, that 
Venus is hot. It suffers from a run- 
away greenhouse effect, induced 
by its atmospheric carbon dioxide, 

18 NATURAL HISTORY May 2004 



which traps infrared energy. So even 
though the tops of Venus's clouds re- 
flect most of the Sun's incoming visi- 
ble light, the rocks and soils on the 
surface absorb the little bit that makes 
its way through. That terrain then 
re-radiates the visible light as in- 
frared, which builds and builds, even- 
tually creating — and now sustaining — 
a remarkable pizza oven. 

The rest of the solar system contin- 
ues to become more fimiliar by 
the day. The first spacecraft to fly past 
Mars was Mariner 4, in 1965, and it 
sent back the first-ever close-ups of the 
Red Planet. Lowell's lunacies noD,vith- 
standing, before 1965 nobody knew 
what the Martian surface looked like, 
other than that it was reddish, had polar 
ice caps, and showed darker and lighter 
patches. Nobody knew it had moun- 
tains, or a canyon system vastly wider, 
deeper, and longer than the Grand 
Canyon. Nobody knew it had volca- 
noes vastly bigger than the largest vol- 
cano on Earth, Mauna Kea in Hawai'i. 

Nor is there any shortage of evi- 
dence that Hquid water once flowed on 
the surface of Mars: the planet has me- 
andering riverbeds as long and wide as 
the Amazon, webs of tributaries, river 
deltas, and floodplains — all bone-dry. 
The Mars Exploration Rovers inching 
their way across the dust and rocks re- 
cently confirmed the presence of sur- 
face minerals that form only in the 
presence of water. Yes, signs of water 
everywhere, but not a drop to drink. 

Something bad happened on both 
Mars and Venus. Could something bad 
happen on Earth, too? Our species is 
currently turning row upon row of en- 
vironmental knobs, without much re- 
gard to long-term consequences. Who 
even knew to question those practices 
before the study of Mars and Venus, 
our nearest neighbors in space, forced 
us to look back on ourselves? 



T 



o get a better view of the more 
distant planets requires space 
probes. The first spacecraft to leave 
the solar system were Pioneer 10, 
launched in 1972, and its twin, Pio- 




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iiccr I /, launched 
in 1973. Both 
passed by Jupi- 
ter within two 
years, executing 



tour 
way. 





a grand 

along the 

Today they're nearl 

8 billion miles from 

Earth — more than twice the distance 

to Pluto. 

When they were launched, how- 
ever. Pioneers 10 and 11 
weren't supplied with 
enough energy to go 
much beyond Jupi- 
ter. How do you get 
a spacecraft to go 
farther than its en- 
ergy supply will 
carry it? You aim it, 
fire the rockets, and 
then just let it coast to its 
destination, falling along the 
streams of gravitational forces set up 
by everything in the solar system. Or- 
bital dynamicists have gotten so good 
at these "gravity assists" that they 
make billiard sharks jealous. 

Pioneers 10 and 11 sent back 
better pictures of Jupiter and 
Saturn than had ever been pos- 
sible, even with the best equip- 
ment on Earth. But the twin 
spacecraft Voyagers 1 and 2 — 
launched in 1977 and equipped 
with a suite of scientific experi 
ments and imagers — were what 
turned the outer planets into icons 
Voyagers 1 and 2 brought the solar sys- 
tem into the living rooms of an entire 
generation of world citizens. And one 
of the windtalls of those journeys was 
the revelation that the moons of the 
outer planets are just as different from 
one another, and just as fascinating, as 
the planets themselves. 

As I write, a NASA orbiter named 
Cassini is hoining in on Saturn, having 
reached the Ringed Planet's neigh- 
borhood after a four-cushion gravity 
assist. Soon Cassini will deploy a 

More paired images of Roman godi paimed 
by Perugino, and the planets named aher 
tliem. Top to bottom; Jupiter and Saturn. 



daughter probe named Huygens 
(designed by the European 
Space Agency) into the atmos- 
phere of Saturn's largest satel- 
ite. Titan, the only moon in 
®y the solar system known to have 
a dense atmosphere. Another 
complex NASA mission now being 
planned is the Jupiter Icy Moons 
Orbiter — JIMO for short. Instead of 
executing a flyby, the JIMO probe 
will carry enough fuel to slow down 
when it reaches Jupiter and enter a 
series of loop orbits, enabling a 
sustained study of the planet's 
sixty-plus moons. 



i: 



n 1584, in his book On 
the Infinite Universe and 
Worlds, the Italian monk 
and philosopher Giordano 
Bruno proposed the existence 
of "innumerable suns" and "in- 
numerable Earths [that] revolve about 
these suns." Moreover, working from 
the premise of a Creator both glori- 
ous and oinnipotent, he claimed that 
each of those Earths has liv- 
ing inhabitants. For 
these and related 
blasphemies, the 
Catholic Church 
burned him at 
the stake. 

Yet Bruno 
was neither the 
first nor the last 
person to posit 
some version of 
those ideas. Others who es- 
poused the concept of multi- 
ple inhabited worlds range 
from the fifth century B.C. 
Greek philosopher Democri- 
tus to the nineteenth-century 
French novelist Honore de 
Balzac. Bruno was just unlucky to 
be born at a time when you could get 
executed for such thoughts. 

During the twentieth century, as- 
tronomers figured that life could exist 
on other planets, as it does on Earth, 
only if those planets orbited their host 
star within the "habitable zone" — a 
swath of space neither too close nor 




too far. No doubt life as we know it re- 
quires liquid water, but it was just an 
assumption that life also requires 
starUght as its ultimate source of energy. 
Then came the discovery that some 
objects in the outer solar system, such 
as Jupiter's moons lo and Europa, are 
heated by energy sources other than 
the Sun. In both cases, the stress of 
Jupiter's tides on the solid moons 
pumps energy to their interiors, melt- 
ing ice and giving rise to environ- 
ments that might sustain life indepen- 
dent of solar energy. 

Even right here on Earth, new cat- 
egories of organisms, collectively 
called extremophiles, thrive in condi- 
tions inimical to human beings. The 
concept of a habitable zone incorpo- 
rateci an initial bias that room tem- 
perature is just right for life. But som.e 
organisms thrive at several hundred 
degrees Fahrenheit, and find room 
temperature downright hostile. To 
them, we are the extremophiles. 

So, armed with the knowledge that 
life can appear in places vastly more 
diverse than previously imagined, 
astrobiologists are broadening the 
earlier, and more restricted, concept 
of a habitable zone. And, just as 
Bruno and others had suspected, the 
roster of confirmed exosolar planets 
continues to grow by leaps and 
bounds. Their number has now risen 
past a hundred — all discovered in the 
past decade. 

Once again we res- 
urrect the idea that 
life might be 
everywhere, just 
as our ancestors 
had imagined. 
But today we do 
so without risk 
of being immo- 
lated, and with the 
newfound knowledge 
that life is hardy, and that the habit- 
able zone may be as large as the 
universe itself. 

Astrophysicisi Neil deGrasse Tyson is 

tlic Frederick P. Rose Director of tlie Haydeii 
Planetarium in New York City. 




20 NATURAL HISTORY May 2004 



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FINDINGS 



Of Mice, Men, 
and Genes 



The best-laid plans o' DNA 
gang aft agley. 

By Robert M. Sapolsky 



w. 




Beatrix Potter: Hunca Munca {from The Tale of Two Bad Mice), T904 



Don't you love urban legends, 
those outrageous stories ev- 
eryone believes? There are 
academicians who study urban legends 
for a living; they catalogue them, track 
their origins in Norse mythology, get 
into arguments at conferences about 
them. But amid all that inteUectualiz- 
ing, it's just plain fascinating to hear 
some of the made-up stuff that lots of 
people fall for. There's the endlessly re- 
peated one about the poodle stuffed 
into a microwave to get dried off, or 
the classic about the scuba diver who 
gets scooped up along with a lot of 
water into the giant bucket of a fire- 
fighting plane, then is dropped onto a 
forest fire. And there's the one about 
the woman who leaves groceries in 
her car on a sweltering day: a tube of 
cookie dough explodes from the heat 
just as she gets back in, splattering the 
back of her head, and she's convinced 
she's been shot and the dough is her 
splattered brains. 

And then there's the one about a 
bunch of scientists who sequenced 
the human genome: they can explain 
everything about you; all they have to 
do is look it up in the sequence of 
your genes. But it just ain't so: we're 
back in the domain of urban legend. 
Why are people such suckers for the 



idea that genes are the be-all and end- 
all? The tendency is particularly bad 
right now. Not only has the human 
genome recently been (mostly) se- 
quenced, but we've also just come off 
the golden anniversary of the discov- 
ery of the structure of DNA. The cel- 
ebrations have been replete with reli- 
gious imagery about the genetic code 
as holy grail, the Code of Codes. And 
this imagery even gets trotted out by 
biologists, people who get paid to 
know better. 

And biologists really should know 
better, because they've had the sober- 
ing concept of "gene-environment in- 
teraction" hammered into their heads 
for much of their lives. (In fact, "gene- 
environment interaction" is probably 
one of the first utterances most biolo- 
gists made as infants, along with "dog- 
gie, doggie come.") The trouble is, it is 
a phrase so often repeated that it has 
become as reflexive and ingrained — 
and, ultimately, ignored — as the words 
to "Elmo's Song." 

The idea that genes and environ- 
ment interact can mean a number 
of things. At the least, it means that 
people who get into black-and-white 
arguments about nature versus nurture 
are a century out of date. Of more rel- 



evance, it means that though genes can 
(indirectly) instruct cells, organs, and 
organisms about how to function in 
the environment, the environment can 
also regulate which genes become ac- 
tive at particular times. Of greatest rel- 
evance here, though, is that the thing 
a particular gene most proximally 
produces — a particular protein — can 
function quite differently in different 
environments. So, in theory, you 
might have a gene that in one environ- 
ment causes you to grow antlers and, 
in another, causes you to fly south for 
the winter. 

For folks who still want to fight the 
nature-nurture wars, the question up 
for debate becomes: OK, just how 
powerful are these gene-emdronment 
interactions? At one extreme are those 
who scoff at contrasts as gaping as the 
one between growing antlers and fly- 
ing south. In their view, a gene does 
something or other, and the environ- 
ment perhaps alters how fast or how- 
strong or how long the gene does that 
something or other. But none of those 
enviromnental influences lead to dra- 
inatically different efiects. Framed in 
the context of genes and disease, it's 
like saying, Yeah, how windy it is may 
alter the precise speed with which the 
anvil drops from a ten-stoiy buUding 



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and lands on your toe, but who cares 
about that environmental interaction 
with the anvil? And at the other ex- 
treme are those who assert that inter- 
actions can be of huge consequence — 
say, if what is dropping is a feather and 
not an anvil. 

And so the scientists happily argue 
and experiment away, squandering 
tax dollars that could otherwise go for 
Halliburton contracts. Amid these 
debates, it's useful to be reminded just 
how powerful gene-environment in- 
teractions can be. Two recent studies 
provide some terrific examples. 

The first study investigated the ef- 
fects of one of the subdest, least 
appreciated environments: the prenatal 
one. For many years, strains of labora- 
tory rodents have been bred for various 
traits — one strain gets a type of dia- 
betes, another strain gets hypertension. 



environmental influence; score one for 
nature over nurture. But are cross-fos- 
tering experiments the last word? 

That's where one of the new stud- 
ies comes in. Carried out by Darlene 
Francis, a neurobiologist at Emory 
University in Atlanta, and her col- 
leagues, it was pubUshed in the presti- 
gious journal Nature Neuroscience. The 
investigators looked at two mouse 
strains that diflTer across an array of 
behavior patterns. To simpHfy a bit, 
one strain is more anxious and skittish 
than the other. Compared with the 
more "relaxed" strain, the "timid" 
strain is slower to enter a scary or 
novel environment, and timid-strain 
mice have more trouble learning dur- 
ing a stressful task than relaxed-strain 
mice do. 

Geneticists who study mice had 
known about those differences for a 
long time. They had also confirmed. 



Environmental influences don't begin at birth: 
the prenatal environment also interacts with genes. 



and so on. Each strain is developed by 
inbreeding generation after generation 
of animals with some trait, until all the 
members of the strain are as close as 
possible to being genetically identi- 
cal — ^Uke clones of one another. If all 
the members of that strain show the 
trait, regardless of which laboratory 
they're raised in, there's some reason to 
think that the animals are subject to a 
strong genetic influence. 

All the inbreeding is then followed 
by an experiment known as a "cross- 
fostering study," regarded as critical for 
detecting a genetic influence. Suppose 
all the mice of the Coke strain grow 
up preferring Coke to Pepsi, and all 
the mice of the Pepsi strain grow up 
displaying the opposite persuasion. 
Take some Coke-strain mice at birth 
and let Pepsi-strain moms raise them 
in a Pepsi-strain colony. If the Coke- 
strain mice stiU grow up craving Coke, 
the typical interpretation is that you've 
found a behavior that strongly resists 

22 NATURAL HISTORY May 2004 



apparently, that the differences were 
largely governed by genetics. True, 
there was some evidence that relaxed- 
strain mothers are more nurturing 
than timid-strain moms, licking and 
grooming their pups more. That evi- 
dence had raised the possibiHty that 
mothering style caused the differences 
between the two strains. But then the 
acid test had been performed: relaxed- 
strain mice that were raised from birth 
by timid-strain moms grew up to be 
just as relaxed as any other member of 
their strain. 

But Francis and her team went a 
step further. With the same kind 
of technology used by clinics per- 
forming in vitro fertilization, the in- 
vestigators cross-fostered mice as em- 
bryos. Specifically, they implanted 
fertihzed eggs from relaxed-strain par- 
ents into timid-strain females, which 
then carried the relaxed-strain em- 
bryos to term. They also did the key 



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control: they implanted relaxed-strain 
eggs into relaxed-strain females (just in 
case the process of in vitro fertilization 
and implantation distorted the results). 
After they were born, some relaxed- 
strain pups were raised by timid- 
strain moms, and others by relaxed- 
strain ones. (If all this isn't confusing 



A finding like this one could give 
panic attacks to mouse mothers the 
world over: Remember the time we 
got all stressed-out when we were 
pregnant? Remember that other time 
we got irritable with our newborn 
pup? One of them could be the reason 
the kid Avon't get into the best college. 




Walking in the Rain, an American postcard from 
the early twentieth century 



enough, at least thank Francis and her 
colleagues for not bothering to im- 
plant fertilized timid-strain eggs into 
relaxed-strain females.) 

And the result? When the suppos- 
edly genetically hardwired relaxed- 
strain mice went through both fetal 
development and early puphood with 
timid-strain moms, they grew up to 
be just as timid as any other timid- 
strain mice. Same genes, different en- 
vironment, different outcome. 

This result raises two points. First, 
environmental influences don't begin 
at birth. Some factor or factors in the 
eiwironment of a timid-strain mouse 
mother during her pregnancy — her 
level of stress, perhaps, or the nutrition 
she gets — is affecting the anxiety levels 
and learning abilities of her offspring, 
even as adults. The mechanisms may 
have to do with alterations in their 
brain structure, hormone profiles, or 
metabolism. In fact, some of the same 
effects have already been documented 
in people. The second point? Relaxed- 
strain mice aren't relaxed only because 
of their genes; their fetal and neonatal 
environments are crucial factors. 



24 NATURAL HISTORY May 2004 



But such worries are far afield, of 
course, from human' concerns. And 
that's where the other study comes in. 

The second recent study is a land- 
mark paper, published in the 
equally prestigious journal Science, by 
Avshalom Caspi, a psychiatrist at 
King's College, London, and his col- 
leagues. These investigators have been 
doing work that puts to shame those 
studies that come out of watching 
some fruit fly with a twenty-four- 
hour life span. Caspi and company 
have been following a population of 
more than a thousand New Zealand 
kids, beginning at age three and con- 



tinuing well into adulthood. 



nigh 



onto a quarter century. Among the 
things they've examined is who, as a 
young adult, suffers from clinical de- 
pression. That topic, by the way, is 
a useful one to get some insight 
about — given that depression can be 
life-threatening and afflicts between 5 
and 20 percent of us. 

Caspi's team examined patterns of 
depression in their subjects and dis- 
(Contiimed on page 31) 



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Nova Scotia 



^Hp ^ contrasts. Our 4,600 

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FINDINGS (Contiiuied from page 24) 



covered that it has something to do 
with possessing a certain variant of a 
gene. That's a nice finding, of course, 
but what makes it really exciting is that 
the gene in question is not just any 
random gene. It has akeady been im- 
plicated in biochemical theories about 
depression, coding for a protein that 
helps regulate how much serotonin 
gets into neurons. Serotonin is a neu- 
rotransmitter, one of scores of differ- 
ent kinds of neurotransmitter in the 
brain, but it is the one responsive to 
antidepressant drugs such as Prozac, 
Paxil, and Zoloft (collectively known 
as "selective serotonin re-uptake in- 
hibitors" — SSRIs). 

The serotonin-regulating gene — 
which for reasons not worth going 
into is called 5-HTT — comes in two 
different "flavors." Both flavors code 
for the same kind of protein, but the 
two flavors differ in how much of the 
protein gets produced. Individuals can 
have two copies of either flavor (one 
from each parent) or one copy of 
both. At least some nonhuman pri- 
mates can as well. Studies had already 
shown that a rhesus monkey's 5-HTT 
makeup affects how readily the animal 
deals with stress. 

So Caspi and his colleagues tabu- 
lated the two 5-HTT gene flavors and 
how they correlated with the inci- 
dence of depression in their pool of 
New Zealand subjects. And what 
they discovered is worth stating care- 
fully. Did they demonstrate that genes 
of a certain flavor actually cause de- 
pression? No. Did they show that 
having a certain 5-HTT makeup sig- 
nificantly increases a person's risk of 
depression? Not really. 

What they showed was that the 5- 
HTT genes you inherit greatly increase 
your risk of depression, but only in a 
certain environment. What kind of en- 
vironment? One with a history of 
major stressful events and traumas in 
childhood or early adulthood (such as 
the death of a loved one, the loss of a 
job, a serious illness). Those in their 
study with a "bad" 5-HTT profile, 
who also suffered major stressful events, 
had almost twice the risk of depression. 



and nearly four times the risk of suicide 
or suicidal thoughts, as those with the 
"best" profile. But those who were 
spared a history of major stresses were 
no worse off for having a "bad" 
5-HTT profile. (Completing this pic- 
ture is work by a group at the Univer- 
sity of Wurzburg, in Germany, show- 
ing that stress hormones regulate the 
activity of the 5-HTT gene, and do so 
differently, according to its flavor.) 

What lessons lurk here? Obvi- 
ously, beware of simple ex- 
planations; it is rare that nature is 
parsimonious. 

And keep genes in their proper 
place. Sometimes genetics is about in- 
evitability. If you have the mutation 
for Huntington's Disease, for in- 
stance, there's a 100 percent chance 
you're going to have this awful neuro- 
logical disease by middle age: no two 
ways about it. But genes are more 
often about vulnerabilities and poten- 
tials than they are about destiny. 

What all this highfalutin molecular 
biology should teach us is that we can't 
just throw up our hands and say: "His 
genes made him do it." We aU have a 
responsibility to create environments 
that interact benignly with our genes. 

Robert M. Sapolsky is a professor of bio- 
logical sciences and neurology at Stanford Uni- 
versity. He is the author of A Primate's Mem- 
oir: A Neuroscientist's Unconventional 
Life among the Baboons. His most recent ar- 
ticle for Natural History, "The Pleasure (and 
Pain) of 'Maybe'" (September 2003), has been 
nominated for the 2004 National Magazine 
Award for Essays. 



Answer to "Cryptic 
Creatures" puzzle 
(page 1 5): b 






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May 2004 NATURAL HISTORY 31 



BIOMECHANICS 



How a Star Avoids the Limelight 

Some echinoderms have thousands of eyes on their backs. 
When the Ughts come on, they switch to wearing shades. 

By Adam Summers ~ Illustrations by Roberto Osti 



f'l^j 



By day, gaudy reef fishes domi- 
nate the scene at a coral reef, 
but by night, invertebrates 
steal the show. Coral polyps — at least 
the ones that can't depend on nutri- 
ents provided by photosynthesizing 
symbiotic partners — extend their 
tentacles in the darkness to feed. 
Feather stars spread their arms, each 
grooved to direct the flow of 
^ ^.^ food to the mouth 



Spiny lobsters march on parade. And 
night is the time to get a good look 
at one of the shiest of all the reet 
dwellers: the brittle star. 

Only at night does the britde star 
venture out of its hiding place to 
snake across the surface of the reef in 
search of food. But divers looking for 
one should be careful with their 
hghts, because shining a light on an 
outstretched limb might just cause the 
animal to hide. 
The reaction 
has always in- 
trigued me, be- 
cause brittle stars 



have no obvious eyes. Nevertheless, 
they can detect light, and a team of 
investigators has now figured out how 
they do it. It turns out the dorsal side 
of the britde star is covered with mi- 
croscopic lenses embedded in its 
skeleton, making the entire back of 
the creature into a compound eye. 



B; 




rittle stars are echinoderms — 
relatives of sea stars and sea 
urchins — and can be distinguished 
from the other groups by their long, 
thin, highly flexible arms and their 
small central disk. But, like all 
echinoderms, they have a hard 
internal skeleton made up of small 
calcite plates, held together by catch 
connective tissue [see "Catch and 
Release," by Adam Summers, 
November 2003] . It has been 
known for decades that some 
of these animals can sense 
light. In the 1980s Gordon 
Hendler, a zoologist at 
the Natural History 
Museum of Los Angeles 
County, and Maria Byrne, a 
developmental biologist at 
the University of Sydney in 
Australia, pointed out that 
members of one brittle star 
species change from their 
nighttime color scheme of 
banded gray and 

black to deep 
brown in the 
daytime. 



Responding to light does not re- 
quire an eye. A sea snake in the sub- 
family Hydrophiinae, for instance, can 
perceive its tail being exposed as the 
snake forages on the reef, and inove it 
out of the Hght. But that response 
would merely require the tail to have 
sensory neurons that respond to 
light — or to heat, the by-product of 
hght on a dark surface. Some brittle 
stars, though, have responses to hght 
that do seem to require an eye. When 
placed in bright sunhght, members of 
those species will make for a shad- 
owed area as fast as their five httle 
arms can carry them. Such behavior 
suggests they can detect shelter at a 
distance and even form an image of 
their surroundings. 

Joanna Aizenberg, a materi- 
als scientist at Bell Labora- 
tories in Murray Hill, New 
Jersey; Alexei Tkachenko, a 
physicist now at the Univer- 
sity of Michigan in Ann 
Arbor; and Stephen Weiner 
and Lia Addadi, both struc- 
tural biologists at the Weiz- 
mann Institute of Science in 
Rehovot, Israel, teamed up 
with Hendler to examine the 
hidden eye of the brittle star. 
The investigators used a scan- 
ning electron inicroscope to 
look at skeletal calcite plates 
from the upper surface of a 
member of the Hght-sensitive 
brittle star species Ophiocoma 
wendtii. What they saw was an 
unusual pattern of densely packed, 
crystal-clear bumps, each thinner 
than a human hair. Similar plates 
from a non-light-sensitive species 
(O. pumila) had no such bumps, and 
neither did plates from the underside 
of the arms of O. wendtii. 

Might the bumps serve as lenses to 
focus light? Aizenberg and her col- 
leagues established good theoretical 
reasons for thinking they could. The 
calcite crystal that makes up a bump 
is ahgned so as to conduct Hght from 
the outside surface of the plate to the 
inside surface. Furthermore, because 
the bumps are not perfect spheres, 



they don't have the blurriness charac- 
teristic of spherical lenses. By mea- 
suring the shape and size of the 
bumps, the investigators calculated 
that they would focus light between 
four and seven micrometers (just a 
few ten-thousandths of an inch) be- 
yond their inner surface. 

Maria Byrne had previously exam- 
ined a plate and surrounding tissue 
with a transmission electron micro- 
scope and found a bundle of nerves at 
the appropriate distance — at the cal- 
culated focal point — from each bump. 
Cells containing pigment reside 
alongside and below each bump. 
During the day, however, the pig- 
mented cells migrate to the upper sur- 




Ophiocoma wendtii, a brittle star (opposite page), prefers the 
dark. But the entire dorsal side of the animal is covered with a 
matrix of calcite crystals (above left) shaped into bumps that act 
as lenses (above right). The lenses (supported by a layer of irregu- 
lar calcite, shown in gray in the schematic diagram) focus incoming 
light on a network of nerves (yellow). Alongside each lens are 
pigment-bearing cells that migrate above the lens layer by day, 
acting as echinoderm sunglasses. Together, the lenses and nerves 
turn the animal's back side into a body-size compound eye. 



face of the calcite ossicles, where they 
shield the top of the lens from the 
bright sun and, incidentally, darken 
the animal. The color change is not a 
camouflage response; rather, it is the 
echinoderm version of sunglasses. 

Following up this work, Aizen- 
berg exposed a sheet of film to 
Hght passing through the presumed 
array of lenses. Her results were 
striking. A small spot of Hght hit the 
film under each bump. The size of 
each spot varied with the size of the 
bump, and the brightness of the spot 
depended on the incident angle ot 
the Hght with respect to the surface 



of the britde star arm. In other 
words, each tiny, embedded bump 
acts as a directional light sensor, re- 
sponding most strongly to light com- 
ing from a particular direction. The 
bump is thus a rudimentary lens. 

If the brittle star had just one such 
lens on each arm, it could look 
around by waving an arm and assess- 
ing the patterns of light and dark. But 
the resolving power of a brittle star 
lens is extremely limited: relying on 
one would be a bit like looking 
through a peephole covered with tis- 
sue paper. Because the dorsal surface 
of the brittle star is covered with 
thousands of tiny "eyes," though, and 
each eye receives light from a sHghtly 
different direction and angle, 
the entire surface can act as 
one large compound eye. That 
compounding makes it pos- 
sible, in some sense, for the 
brittle star to take in the 
whole scene. A computer 
monitor is a useful analogy. A 
single pixel holds information 
about the color and brightness 
of a single part of an image. 
But an entire array of pixels 
yields a coherent picture. 
The brittle star's eye is a 
wonderful example of how 
basic science — in this case 
Hendler and Byrne's natural- 
historical observations — can 
give appUed scientists insight 
into a problem with clear 
commercial impact. Investigators at 
Lucent Technologies (of which Bell 
Labs is a part) are excited because the 
brittle star makes better, smaller lenses 
than they do. They hope to learn the 
secret of depositing a well-patterned 
crystalHne matrix, so they can then 
shrink fiber-optic junctions and ad- 
vance toward the goal of building a 
completely optical computer. As for 
me, I know I'll never again look at a 
britde star in quite the same \\'ay — 
now that I know they're looking back! 

Adam Summers (asummers@uci.edu) is an 
iissistiiiit profcsscr of ecolcgy '""^ evolutionary 
biology at the Uiiipersily 0/ California, Irvine. 



t^/lay 2004 NATUR.M HISTORY | 33 



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Zoology laboratory at Cairo University, part of the Egyptian national educational system. Males 
and females are treated equally when it comes to education, and many urban families encourage 
their daughters to pursue advanced studies rather than rush into marriage. 

Egypt's %uni 
and Restless 

Through Islam and the Internet, a new generation seeks its fair share. 

By Mary Knight 



34 NATURAL HISTORY May 2004 



MAY 2 004 




o 



sama 'Abd al- 
Raheem studies 
engineering at 
Helwan University, in the 
southern suburbs of Cairo. 
He is committed to his 
studies, and, hke most 
young adults, he aspires to 
marry, to find a decent job 
that puts his hard-won 
skills to good use, to hve a fulfilhng life with his 
family, his friends, his culture, his country. But he 
looks with envy on those who are fifteen or 
twenty years older, who were able to buy homes 
and furnish them during the long-vanished days of 
easy money. When we talked, he expressed his 
frustration: "If a young man takes a job in Egypt, 
his salary wiU be about 500 Egyptian pounds [less 
than $100] per month, so he wiU have to work ten 
years to get married; if he goes abroad, he can get 
married much sooner." 

The disadvantage Osama must live with is that 
going abroad today is not the solution it was for 
young men twenty or more years ago. In the 1970s 
and 1980s, when the prospects at home were Uttle 
better than they are today, Egyptian laborers, 
mostly male, traveled to the oil-rich Gulf states and 
nearby Libya for work. The income they brought 
or sent back home enhanced living standards for 
many families. Overall, in fact, poverty declined. 

Then, with the coUapse of OPEC's power and 
the crisis brought on by the 1991 Gulf War, many 
would-be Egyptian migrants had little choice but 
to stay home. For men, the blow was particularly 
harsh: often they could find no work in their fields 
of study, and what httle money they did earn was 
not enough for the down payment on an apart- 
ment, a prerequisite for marriage. For Osama, the 
foreign safety valve has closed shut. 

Many young Americans can probably empathize 
with Osama's pHght. Ambitious, highly educated 
graduates are often thrust, when they first enter the 
workforce, into low-paying and exhausting dead- 
end jobs, just to make ends meet. But the situation 
in Egypt is far more desperate than it is in the 
United States. With 72 million people, Egypt is the 
most populous of the twenty-two Arab states. Offi- 
cially the nation's unemployment rate is only about 
9 percent. Studies that specifically track youth 
unemployment, however — in a nation where the 
median age is twenty — estimate that 25 percent of 
men and 59 percent of women are without work. 
As in the U.S., these studies include only people 



who are actively seeking a job, and part-time work- 
ers are considered employed. 

Unemployment, though, is only one way to un- 
derstand the plight of the young people in this large 
Arab country. Another set of critical issues is the 
distribution of power — which in Egypt largely co- 
incides with the distribution of wealth — and the 
perception that the distribution is unjust. The class 
difference is rarely discussed as such, but it is cer- 
tainly noticed, and it plays a major role in gaining 
access to such basic social services as technical train- 
ing. Social gaps everywhere — between rich and 
poor, young and old, educated and iUiterate, urban- 
ite and farmer — reinforce the corrosive perception 
that the society does not reward its citizens on merit 
alone. The resounding cries by youth of "it's unfair" 
often turn on income disparity. 

Among those whose voices are raised are the 
Islamic militants, many of whom are men from 
relatively privileged backgrounds, familiar with 
Western ways. What often incites their anger is 
seeing their parents operate on principles other 
than those of idealistic fairness. And when these 
young men meet other, less privileged people 
who have substantial talents and abilities that are 
passed over by the Hkes of their parents, their out- 
rage may grow to conspiratorial proportions. 



Last fall I traveled to 
Cairo, a city where 
I've Hved and worked 
on and off since 1994. 
Because I have many 
friends and contacts 
there and am reason- 
ably fluent in the lan- 
guage, I was in a good 
position to take the 
pulse of the so-called 
Arab street. My aim 
was to sketch how or- 
dinary hves are lived in 
a culture that Ameri- 
cans have largely ig- 
nored — ignored, that 
is, until they "learned" 
recently to regard vir- 
tually all Arab culture 
with fear and suspicion. 
The immediate ques- 
tions that dog my fel- 
low Americans — Why 
do they hate us? What 




Girls take part in a science class taught in 
English, at al-Nozha Language School, an Islamic 
school on the outskirts of Cairo. Such schools are 
generally better equipped than the state schools, 
but their numbers are limited. 



May 2004 NATURAL HISTORY 35 



do they think of our poUcies? — were not my first 
priority, though. My focus was to understand 
Egyptian concerns; to learn how Egyptians were 
facing up to universal questions about access to 
hi,gh-quality education, women's evolving social 
roles, and career development; and to find out how 
their deeply held reHgious beHefs affect their inter- 
action with the world at large. 

At the root of Egypt's dismal unemployment 
statistics are the nation's weakness in the production 
and dissemination of knowledge and the govern- 
ment's inadequate commitment to science and tech- 
nology. Yet there is tremendous energy and enthusi- 
asm for learning among Egyptian students. Every 




his friends told me that as many as sixty students 
typically crowd around their professor as he performs 
experiments for the class. The reason is that nearly all 
of the aging equipment is broken. "The classes are 
crowded," he says, "so it's hard for the students to 
understand. So we just memorize the lessons." 
Memorization is still the preferred method of learn- 
ing in all disciplines, but in the sciences, the near 
total lack of hands-on experimental work suppresses 
the critical and creative skills needed to excel. 

Painfully aware that their futures rest on the suc- 
cessful use of mouse and keyboard, Egyptian young 
people seek out the new technology. Cybercafes 
and computer training institutes now abound 
throughout Cairo, though all charge 
relatively high fees. Industrious 
youths save up the 2,000 to 3,000 
Egyptian pounds (between $400 and 
$600) needed for a computer, then 
add peripherals, often secondhand, as 
their budgets permit. In the past few 
years, Egypt's relatively open society 
has helped the country surpass most 
of the rich Gulf states in factors that 
measure computer-related growth. 
Internet connections, for instance, 
are now free, though the phone 
charges, which are based on the 
amount of time spent online, are rel- 
atively expensive. That said, the per- 
centage of all Egyptians who have 
ever accessed the Internet remains in 
the single digits. 



A bride, left, sports her wedding hairdo the night before the ceremony. 
Solemnization of the union is performed at a mosque, but the bride's family 
usually puts on a wedding reception. The groom is responsible for supporting 
himself and his bride, and — because a large deposit is required to establish their 
new residence — he must have accumulated considerable savings. 

young person I spoke with acknowledged the need 
for job-related computer skills and for better access 
to information in a country where libraries are only 
now becoming more widely accessible. 

The Ministry of Education likewise recognizes 
the need for computer skills, and so it has provided 
every public school in Egypt with at least one 
computer, and occasionally more than one. But 
school enrollments usually number in the hun- 
dreds, and the presence of one or two computers 
normally restricts usage to demonstrations by 
teachers at the front of the class. 

Perhaps even more detrimental is the lack of func- 
tioning, up-to-date laboratory apparatus in science 
education. Osama 'Abd al-Raheem and several of 



A: 



mong those energetically devot- 
ing themselves to improving 
the lot of young people are what 
are coming to be called the "new 
Islamists" — Muslims who believe 
their primary duty is to Hve exem- 
plary lives and thereby iinprove the community. (By 
contrast, militants strive first to rid the world of dis- 
believers, condoning violence in the process.) 
Hosam Muhammad, a sturdily built twenty-nine- 
year-old, and his colleague Hisham Muhammad, a 
fme-boned, quiet-mannered twenty-three-year-old, 
both teach EngUsh in al-Nozha Language School, a 
clean and orderly Islamic school on the northeastern 
outskirts of Cairo. The school serves about a thou- 
sand students, from kindergarten through high 
school. Both men use the Internet to enhance their 
knowledge and to make friends with English speak- 
ers around the world, particularly in the U.S. 

In their jackets and ties, dress slacks, and pol- 
ished shoes, the two Arabs, one clean-shaven and 



36 NATURAL HISTORY May 2004 



the other wearing a neatly trimmed beard, look 
like refmed, educated young professionals any- 
where. Pohte and modest, they laugh readily and 
banter charmingly, in English or in Arabic. And 
both strongly maintain that Islam has a transforma- 
tive, restorative power for their society. In the 
classroom they teach values through example, as a 
way to complement their curriculum of intensive 
language training. Their ultimate jihad is to push 
their students along the path to a better future, 
both economically and morally. 

Another "new Islamist" is 'Abd al-Hafiz al- 
Sayyid Muhammad, the imam, or chief religious 
leader, at Omar Makram Mosque in downtovv'n 
Cairo. In 1995, recognizing the need 
for knowledge and the traditional role 
of the mosque in education, 'Abd al- 
Hafiz initiated computer courses in 
rooms above the prayer hall, diverting 
some of the mosque's funding to the 
purchase of computers. (Literacy classes 
were already in place, for men and 
women.) Students — more than a thou- 
sand a year — flocked to the innovative 
program, not only to learn computer 
skills but also to learn English and a 
variety of vocational skills. 

Women like Nermeen 'Abd al- 
Tawab, a vivacious twenty- 
eight-year-old at the University of 
Cairo's Faculty of Agriculture, exem- 
plify another vibrant part of Egypt's 
young generation. Her specialization, 
agricultural research, is one of the few 
bright spots in Egyptian science, per- 
haps because 44 percent of Egyptian 
workers are employed in agriculture. 
She studies the fungal infection white 
rot in garhc. White rot has important 
economic consequences, because it often devas- 
tates the bulbs as the garlic goes to market. As part 
of her doctoral research, Nermeen is applying the 
tools of biotechnology to develop garUc that is re- 
sistant to the virus. Thus occupied, she is postpon- 
ing marriage untU she finds someone she loves and 
respects. Her family supports her plan completely. 
Compared with urbanites, girls from rural areas 
are apt to find less family support for their educa- 
tion, particularly when one or both of their parents 
are illiterate. Rural parents encourage their daugh- 
ters to marry at earher ages, even if that means mar- 
rying a first cousin (usually not a girl's preference). 
But in Cairo education is a lifeline for many fe- 
males, giving them hope and freedom no matter 



how humble (or how high) their origins. While 
they are in school, they don't have to compete for 
jobs that are unlikely to be offered to them anyway. 
And if they enjoy studies, they have the chance to 
learn more than any of their predecessors and to be 
respected for their achievements. 

The social barriers to women in Egypt are by no 
means as stringent as they are in Muslim countries 
that impose a strict interpretation of Islamic law. 
Some Egyptian women even initiate divorce. 

Mai Mostafa, a tall, slender thirty-two-year-old 
designer and artist, elaborated on the hazards of 
poor mate selection and divorce: "For every 
woman who lives in the East, marriage is very im- 




A cafe, serving tea, light meals, and other refreshments, offers a place for 
young men to socialize. For some, though, the cafe is the introduction to a 
life of permanent idleness. Unemployment is high in the outsize generation 
of young adults, and the opportunities that once existed for work in the 
Gulf states and nearby Libya have been closed off. 



portant. We've been brought up prepared to be- 
come wives later. We have a saying that the woman 
who dares to ask for a divorce helps the house col- 
lapse." Mai's father encouraged her to complete her 
education and to work for a few years, to become 
independent-minded and self-reliant. He did not 
exactly approve of her marriage partner, but assured 
her of his confidence in any choice she made. After 
the marriage failed, Mai was grateful that, again, 
her father supported her decision to get divorced. 

In spite of the recognition of the need, attempts 
to estabhsh world-class research and educational 
institutes in Egypt have foundered. Alimed Zewail 
of the Cahfornia Institute of Technology in Pasa- 



M ay 2004 N.\TURAL HISTORY 



dena, the Egyptian- American who won the 1999 
Nobel Prize in Cheinistry, convinced the govern- 
ment to build a state-of-the-art university for sci- 
ence and technology. More than four years after the 
gipund-breaking ceremony, however, his dream has 
yet to be realized. 

For most young people, then, the only option is 
to leave the country, a choice that simply exacer- 
bates the already pernicious brain drain. One stu- 
dent I met in Egypt two years ago, who received a 
grant to study in a computer sciences department at 




Transit workers besiege their union headquarters, simply to 
press bureaucrats into processing their papers and 
applications for routine benefits such as medical care, life 
insurance, credit, pensions, and discounts on housing. 

a U.S. university in the Midwest, assured me he 
would return to Egypt after completing his Ph.D. 
program. When I spoke with him more recently, 
he was equally fervent in his insistence that he has 
no plans to return. The reason? In the U.S. he can 
do research that builds on the latest developments 
and can produce work others will draw on. He'll 
stay in the loop, rather than outside it. 

According to the 2003 Arab Human Develop- 
ment Report of the United Nations Devel- 
opment Programme, the uneven distribution of 
income is a critical obstacle to reform and progress. 
Estimates of extreme poverty in Egypt range from 
30 to 40 percent of the population, much of it con- 
centrated in the rural areas, where about 55 percent 
ot the people live. In Cairo, perhaps 20 percent are 
truly poor; the vast majority of people are of mod- 
est means and must rely on free social services and 
education to improve their lot in life. 

But their options are severely restricted. For ex- 



ample, on the basis of their grade on the thaiiawiyya 
'amma, a single national test given at the end of sec- 
ondary school, young people are assigned a profes- 
sion, such as physician, accountant, tour guide, and 
so on. High scorers have the right to choose a 
"lesser" profession than the one they qualify for, but 
they normally don't, because of the social stigma 
attached. Nor do they have the option of taking a 
year off to think about career choices. Young people 
entitled to go on to higher education are assigned to 
a university, which often involves a two-hour daily 
commute in each direction (and studying is nearly 
impossible on the overcrowded buses or trains). 

None of these problems exist, of course, for the 
tiny minority of people who have money. The in- 
fluence of wealth only begins at school; it extends 
to the upper echelons in all walks of Ufe, a fact that 
has provoked widespread concern. In particular, 
the unfairness of the yawning gulf between the 
haves and the have-nots has engendered the out- 
rage that has led Islamic militants to pursue their 
restrictive interpretation of reUgious law. But in 
conversations with militants fi^om both modest and 
privileged backgrounds, I have heard a common 
theme: many militants would rehnquish their arms 
if the laws already in existence were applied fairly 
and equally. 

A comparison to the U.S. youth movement of the 
late 1960s and early 1970s — when, similarly, super- 
size cohorts of impatient, ideaHsric young people felt 
largely left out of the political process — is tempting. 
No, Egyptian youth are not staging sit-ins and crash- 
ing the gates of the political arena. But the reason 
they aren't may have more to do with the class bar- 
rier and the skewed demographics of sitting poHti- 
cians than any lack of political will. A substantial 
number of Egyptian ministers are more than sixty- 
five years old, belonging to an age group that makes 
up just 2.2 percent of the population. Most youths 
cannot visualize themselves in positions of power. 
What they hope for is that someone they trust, 
whether judge or religious leader or someone else in 
tune with their needs, will demand and achieve for 
them the fairness that, in principle, the law asserts. 

Although the government seems litde moved by 
the youth crisis, there are promising signs of 
reform through the youth committee of the ruling 
National Democratic Party (NDP). The commit- 
tee's head, Mohamed M. Kamal, is especially en- 
couraged that though nearly 70 percent of the pop- 
ulation is under thirty, qualified people are finding 
work in the private sector. 

Leading citizens have also initiated projects not 
only through Islamic institutions but also through 



38 NATURAL HISTORY May 2004 



governmental and nongovernmental organizations 
(NGOs), and many of these reform efforts target the 
young. Approximately 16,000 NGOs now respond 
to the needs of civil society in Egypt. "We have 
proven as Egyptians, as Arabs, as Muslims that we 
can be very successful," asserts Hesham Dinana, a 
hard-driving thirty-nine-year-old engineer oversee- 
ing construction of a new children's cancer hospital 
in Cairo (it is dubbed Hospital 57357, after the 
number of the bank account that takes donations). 
Hesham spent more than a dozen years climbing the 
corporate ladder in the U. S. before returning to 
Egypt to contribute to this "people's project." With 
donations from across the classes, the cancer hospi- 
tal, probably the largest NGO in Egypt, is proof that 
the Egyptian people are willing to share the burden 
to reduce the epidemic of childhood cancers. 

Many young people do express hope for the fu- 
ture. Perhaps the most unusual source of optimism 
for the young is the media. Egyptian national tele- 



vision, long dominated by the monotonous recita- 
tion of news briefs and a parade of sleepy soap op- 
eras, faces a challenge in attracting the youth, who 
have turned to the satellite channel al-Jazeera, based 
in Qatar. Hussein 'Abd el-Ghani, Bureau Chief of 
al-Jazeera's Cairo office, boasts that the satellite 
channel "is the first rehable source of news for the 
young," and it is now the most-watched station 
among the youth of Egypt, according to the results 
of a recent survey. Young people told me they hke 
its edgy style, its fast pace, and its no-sacred-cows 
approach to topics and people. Not only advertisers 
should be pleased by the numbers, because it's get- 
ting young people to think about politics, talk 
openly and critically about national and interna- 
tional events, and reaUze they deserve a place in 
shaping their nation's future. Although provocative 
for the region, al-Jazeera helps release some of the 
frustration felt by Egyptian youth. And it affirms 
their identity as young, strong, and Arab. D 




Professor, left, teaches a class at the Women's Medical Faculty of Cairo's al-Azhar University. 
Because such state-run facilities generally face a shortage of modern laboratory equipment, 
instruction emphasizes lectures and demonstrations instead of hands-on learning. 



May 2004 NATURAL HISTORY 39 




A Birthstone 
for Earth 

The oldest terrestrial material is a crystal of zircon, 
the sometime diamond substitute that can be 
a geologist's best friend. 

By Edmond A. Mathez 



With a wave, we bade good-bye to our 
helicopter and watched as it disap- 
peared over the horizon. In the sud- 
den stillness, the seven of us stood at the edge of 
Greenland's ice cap, in a remote corner of the 
world, cut off from the rest of humanity by many 
miles of impassable lakes, glaciers, and fjords. 

Perhaps some people would be unnerved by the 
isolation, the stark surroundings, the cold wind 
blowing off the ice cap, and the prospect of living 
in tents in unpredictable weather. But we seven 
geologists were a happy crew. Some of us had been 
friends for years; others were new to the area and 
the people. But all of us shared the excitement of 
at last reaching this remote place. We had come to 
Greenland in search of the oldest rocks known to 
have originally formed on Earth's surface, de- 
posited some 3.8 biUion years ago. And now we 
shared a sense of anticipation that on this trip we 
might get lucky enough to satisfy our curiosity 
about conditions on Earth long ago. 

The rocks we sought are embedded in a bow- 
shaped band known as the Isua supracrustal belt. 
The band runs about twenty-five miles long and a 
few miles wide, inland from and high above the 
spectacular fjords of southwestern Greenland. Orig- 
inally the rocks of the Isua belt were mostly lavas 
between which were sandwiched a few sedimentary 
beds. In the billions of years since their deposition, 
they have been buried as deep as twelve miles, 
heated to temperatures as high as 1,000 degrees 
Fahrenheit, simmered in chemically reactive fluids, 
folded, and faulted. What's more, the process has 
taken place not once, but three times. 

That tortured history, all part of what is com- 
monly called metamorphism, has resulted in the cre- 
ation of a completely new set of minerals made from 
the chemical components of the original ones. 



Stresses acting on the rocks 
caused the newly formed miner- 
als to realign, completely de- 
stroying the original layering. 
The original rocks changed com- 
position as they reacted deep 
in the Earth with passing fluids. 
After such a beating, it is the rare 
rock that is recognizable in the 
field, even to the most expert 
eye, as having once been a lava 
or a sediment at all. 

Given the destruction of the 
original evidence, what basis 
do geologists have for claiming 
that the Isua belt is 3.8 billion 
years old, or that the rocks have 
been metamorphosed multiple 
times? The evidence, in part, is zircon. Zircon? The 
mineral best known as a jeweler's low-budget sub- 
stitute for diamonds and other precious stones? 
But zircon turns out to be so durable in nature 
that, for students of the ancient Earth, it too is a 
symbol of "forever." 




T 



he name "zircon" comes from the Arabic 
zarqilii, which itself comes from two Persian 
words meaning "gold color"; thanks to trace quan- 
tities of iron, most zircon crystals are yellowish 
brown or gold in hue. (Most of the zircon used for 
jewelry is heated to render the crystals pale blue.) 
The ideal chemical formula is ZrSi04, or zirco- 
nium silicate. Zircon occurs widely in rocks — par- 
ticularly granites, which are rocks comprised 
mainly of the minerals quartz and feldspar and 
which make up a large portion of the continental 
crust. But zircon is rarely present in large quantities 
in any one rock, making it what geologists call an 



40 NATURAL HISTORY May 2004 




Rock constituting Greenland's Isua supracrustal belt was originally made up of lava sandwiched 
among a few sedimentary beds. After deep burial, chemical change, and uplift, the rock was 
substantially altered. But minuscule crystals of zircon, embedded in the rock, resisted the 
changes and so can help geologists reconstruct the process. A 208-carat zircon gemstone is 
pictured at the upper left of the opposite page. 



accessory mineral: a mineral present in such meager 
quantities that geologists usually pay it little heed. 
But zircon has some important properties that to- 
gether conspire to rescue it from obscurity and 
make it one of the most important tools geologists 
have for studying the long distant past. 

Zircon's first important property is its resistance 
to weathering. It measures 7.5 on the Mohs hard- 
ness scale. By comparison, talc, the softest known 
mineral, has a hardness of 1; diamond, the hardest 
known mineral, rates a 10; and in between are ma- 
terials such as glass (5.5) and the hardened steel used 
in making files (6.5). To appreciate the importance 
of that property, suppose a zircon crystal, one-ten- 
thousandth of an inch long, forms in a chunk of 



granite that has soUdified twelve miles below Earth's 
surface. With time, the granite happens to be up- 
lifted to the surface, perhaps even pushed high 
into a mountain range at the edges of two colliding 
tectonic places. Once exposed to air and water, 
though, the granite erodes, but the zircon within it 
usually survives. As the mountains gradually wear 
away, the zircon is washed down mountain streams 
and becomes part of the sediment accumulating in 
river beds or deltas, or along a coastUne. 

The second important property ot zircon is that 
it resists chemical attack. As sandy sediment builds 
up, any zircon crystals in it are buried, and the sed- 
iment is compressed into brittle sedimentary rock. 
With deep burial, the rock is cooked by heat and 



May 2004 NATURAL HISTORY 41 



RIFTING BE6IMS 




Plates collide 

RAPID UPLIFTiNS 
FORMS MOUNTAIN 
RANGES 



Episodes of mountain building commonly follow the so-called Wilson cycle. Continental 
crust (V begins to rift under pressure from the mantle (2). The rifting splits the continent, 
and the upwelling magma creates an ocean basin (3). Eventually, the ocean basis begins 
to close again, forcing the denser oceanic lithosphere to subduct, or slide under, the more 
buoyant continental crust. The subducting lithosphere and overlying mantle partially melt, 
and the molten rocks punch upward through the overlying continental crust to create a 
chain of volcanoes (4), such as those found in the Andes of South America and the 
Cascades of North America. The ocean basin continues to close (5) until the two 
converging continents collide (6). Such collisions force rock upward along the continental- 
plate boundaries, creating massive, nonvolcanic mountain chains, such as the Himalaya. 
As the new mountains erode and shed their sediment into flanking basins (7), buried rock, 
no longer so weighed down, rises to the surface. The process begins anew when the 
continent is split apart by slow but unceasing motions of the underlying mantle. 



and accreting a second, younger 
overgrowth. 

The conclusion of the story 
is simple yet jawdropping. Each 
overgrowth is analogous to a 
tree ring — except that instead of 
recording annual episodes of 
growth, the rims on zircon crys- 
tals record multiple geologic cy- 
cles. Each cycle begins with uplift 
and mountain-building, contin- 
ues with the erosion of towering 
mountain ranges, and concludes 
with the burial of the erosion- 
derived sediments as the moun- 
tains wear down to plains, setting 
the stage for the cycle to begin 
again. And each cycle commonly 
lasts hundreds of iruUions of years. 



t: 



pressure into a hard, crystalline, metamorphic rock. 
Indeed, the rock may partially melt if the tempera- 
ture is high enough. In any case, at least part, and 
possibly all, of the original zircon grains, because of 
their chemical durability, usually survive. 

The next stage in the process is critical to geolo- 
gists' fascination with zircons today. At some point 
in the metamorphic process, a coating — a slow- 
growing rind that geologists call a rim — com- 
monly grows around the original crystal. The new 
metamorphic rock, therefore, contains a znron 
crystal with both a core that is older than the rock 
itselt and a zircon overgrowth that formed at the 
same time as the new rock formed. It is not hard to 
imagine what happens when the new metamor- 
phic rock is exposed at the surface by uphft and 
then becomes eroded. That same zircon crystal, 
with its old core and younger rim, inay again rise 
into jagged mountains, and again get washed away 
as those mountains erode. Continuing to retrace its 
earher history, the zircon may then become incor- 
porated into sediment and, once more, find itself 
deeply buried in even younger metamorphic rock. 



' he fact that such cycles 
exist — let alone that they 
are recorded by such tiny, seem- 
ingly innocuous, crystals — may 
sound incredible, and so a brief 
digression is in order. The moun- 
tain-building stages of these cy- 
cles, as I suggested earlier, result 
from plate tectonics, the primary 
force shaping the surface of our 
planet. Like an egg, Earth pos- 
sesses a relatively rigid outer shell, 
known as the lithosphere. Driven by the slow but 
inexorable convective motion of hot rock in the 
mantle below, the lithosphere breaks into plates that 
constantly move away from, coUide with, and grind 
against each other. In the process the plates are con- 
tinually destroyed and reformed. The lithospheric 
plates themselves are about sixty iniles thick, and 
the lighter rock that makes up the continents, typi- 
cally twenty-five miles thick, floats on top of them. 
As the continental masses are carried about on 
the surface by the motion of the underlying plates, 
those masses, too, are continually crunching to- 
gether and combining into large "supercontinents," 
then separating into smaller continents, and even- 
tually recombining in some new arrangement. 
Great rifts open up where continents puU apart, 
and eventually seawater pours in to fdl the rift; a 
good example is the Red Sea. Mountains rise along 
the margins of continents as material is squeezed 
upward where the plates coUide. The Himalaya, for 
instance, are still rising at local rates of nearly half an 
inch a year as the Indian subcontinent grinds its 
way northward into Asia. 



42 NATURAL HISTORY May 2004 



Rapid uplift is generally accompanied by rapid 
erosion, as well as the formation of flanking sedi- 
mentary basins. There the eroded material, includ- 
ing zircon, accumulates. When the converging plate 
motion ceases, the mountains stop growing, and 
erosion eventually wears them down. The Alps are 
an active mountain belt today that was created by a 
collision between the Eurasian and African plates. 
The Appalachians were once much like the Alps. 
Should the Adantic Ocean begin to close in a hun- 
dred million years or so, the Appalachians will again 
become an active, growing mountain chain, and the 
deep, basement rock that supports them will be up- 
lifted and exposed to the surface. The cycle is des- 
tined to continue. 

This story of dynamic but cycHc change would 
be nothing more than empty hypothesis it 
rocks left no record of their ages. But zircon has a 
third important property that satisfies the need for 
evidence: it can accommodate atoms of certain ra- 
dioactive elements into its crystalline structure, and 
those elements can act as long-running clocks from 
which the age of the zircon can be read. The most 
important of those elements is uranium, which 
readily substitutes for zirconium in the crystal 
structure because the ions of both elements have 
the same charge (+4) and roughly the same size. 
The radioactive uranium locked up in the zircon 
decays to lead at a fixed 
rate. By measuring the rela- 
tive abundance of those 
two elements in the zircon 
today, one can determine 
how long ago it formed. 

Perhaps unsurprisingly, 
the reality of dating a 
zircon is less simple than 
the foregoing explana- 
tion might suggest. One 
complication is that when 
zircon is heated during 
burial, some of the lead 
that had accumulated from 
radioactive decay can dif- 
fuse out of the crystal. The 
loss of that lead changes 
the ratio of lead to ura- 
nium, and so the new ratio, 
if measured, would give a 
spurious age. 

Fortunately, there is a 
way around that problem. 
To date zircon geologists 
rely on two isotopes of 



uranium. The isotope uranium-238, with a half- 
life of 4.468 billion years, decays to lead-206, while 
uranium-235, with a half-life of 703.8 million 
years, decays to lead-207. (The half-life is the time 
it takes for half the original "parent" isotope — ura- 
nium, in this case — to decay to the "daughter" iso- 
tope — ^lead. In one half-life, half the parent isotope 
remains; in two half-lives, a half of a half, or one 
quarter, remains; and so on. Age is calculated by 
measuring the amounts of parent and daughter iso- 
topes present.) Thus in zircon, two difierent clocks 
are ticking away at different rates, and comparing 
the ages ineasured from both clocks is a cross-check 
on each of them. If the two ages are mutually con- 
sistent, the dating is probably accurate; if they are 
not, the zircon has lost or gained uranium or lead 
some time since its formation, and so neither date 
can be trusted. 

A second compUcation for dating zircon is that 
analyzing isotope ratios only in a zircon over- 
growth or only in a core is not so easy. The reason 
is that those features are usually just a few ten-thou- 
sandths of an inch across, and the layers of over- 
growth are not always visible in cross section, even 
under a high-power microscope. Yet to get an accu- 
rate picture of the history of a zircon, distinguishing 
one region from another is critical. Analyzuig a zir- 
con made up partly of material from the 3.5-billion- 
year-old core and partly 
fr-om the bUHon-year-old 
overgrowth would give a 
meaningless age. 

Fortunately, there are 
now a few techniques, 
fairly simple (at least in 
principle), for imaging the 
different growth zones of 
zircon. One is to view the 
mineral in cathodolumi- 
nescence [see photomicro- 
graph on next page] . When 
the zircon is bombarded 
by high-energy electrons, 
It emits visible light. Be- 
cause of subtle variations 
in the zircon's composi- 
tion, the brightness of 
the emitted light is not 
uniform, thus revealing 
the zircon's core and its 
growth zones in a photo- 
micrograph. 

To determine the con- 
centrations of the uranimn 




^OrmeD^^^ 



Zircon follows its own cycle, closely intertwined with the 
Wilson cycle. A zircon grain may first form in solicfifying 
molten rock (1), such as granite. When the granitic body, 
with its enclosed zircon, is uplifted and exposed at the 
surface (2), erosion and deposition lead to zircon-bearing 
sedimentary rocks (3), which are buried and "cooked" 
into metamorphic rock (4). More zircon precipitates onto 
the existing crystals (1), and the process begins again. 



IVlay 2004 NATURAL HISTORY 43 



and lead isotopes in micro- 
scopic regions in the zircon, 
geologists rely on a tech- 
nique known as secondary 
iori mass spectrometry. An 
instrument known as an 
ion probe bombards the 
polished surface of a zircon 
with a beam of narrowly 
focused high-energy oxy- 
gen ions. The ions erode 
the surface, a process that 
creates a shallow pit and 
causes secondary ions to 
emanate from the zircon. 

The secondary ions are 
accelerated oif the sample 
by an electric field and 
directed into a mass spectro- 
meter, an instrument that 
collects, sorts, and counts 
the ejected ions according 
to their masses. The instru- 
ment's ability to precisely 
analyze and date specific, 
identifiable microscopic re- 
gions of a crystal is what 
makes zircon dating such a 
powerful geologic tool. 




Our team had come 
to Greenland to ex- 
plore Isua further and to 

seek more precise information than had been avail- 
able before about the age of the belt. Our long- 
term ambitions were to read those ancient rocks 
closely enough to gain an understanding of the 
conditions on the surface of the early Earth and 
how and when the first continental crust was 
formed. Long ago, in our planet's earUest days, it 
became differentiated into distinct layers: a dense, 
metallic core, a silicate mantle, a less dense silicate 
crust, a water ocean, and an atmosphere. That dif- 
ferentiation remains one of the most significant 
events in the planet's history. The resulting archi- 
tecture determined much of Earth's later develop- 
ment, and is one of the reasons we human beings 
and other animal life emerged here. 

The ancient Hneage of the rocks in the Isua belt 
makes them crucial in developing a picture of Earth's 
early history. Fortunately, zircons occur in many old 
crustal rocks, and the distribution of their ages sug- 
gests that only small bits of incipient crust existed at 
the time the Isua rocks formed, and that the crust 
grew rapidly thereafter. Hints about the extent and 



Photomicrograph of zircon crystal (top) is not particularly 
informative for a geologist hoping to date a roc(t that 
contains such a crystal. But if the crystal is bombarded 
with electrons, it emits light known as cathodo- 
luminescence, revealing a layered internal structure 
(middle photomicrograph and lower diagram). Each layer 
is like a tree ring, representing one cycle in the process of 
deposition of zirconium silicate around an original seed 
crystal. Once the layer boundaries have been determined, 
geologists can sample and date each one. For the layers 
shown here, zones 1 and 2 are both 3.7 billion years old 
(zone 2 looks different because of corrosion): zone 3 is 
3.6 billion years old; and zone 4 is 2.6 billion years old. 



riming of the differentiation 
of the crust from the man- 
tle can be coaxed from the 
detailed geochemistry of 
Isua lavas. But to make 
sense of the geochemistry, 
geologists need to become 
more certain about the age 
of the rock. 

More accurate dating of 
the Isua belt may help tlU 
in more than just the geo- 
logical history of Earth; it 
can also give a better sense 
of when life originated. 
Direct evidence indicates 
that life was present on 
the planet at least 2.7 bil- 
lion years ago and possibly 
as long ago as 3.5 billion 
years (though the fossil ev- 
idence for the earUer date 
is controversial). But cer- 
tain Isua rocks indirectly 
suggest that Hfe existed be- 



fore then. 

The evidence comes 
from yet another isotopic 
ratio. Carbon, which is a 
major part of all living 
tissue, occurs naturally in 
two stable isotopes, car- 
bon-12 and carbon-13. 
And carbon incorporated in living tissue by photo- 
synthesis presents an exception to a general rule of 
chemistry: that two isotopes of the same element 
are chemically indistinguishable. In fact, atoms of 
carbon- 12 and carbon-13 bond with slightly differ- 
ent strengths to other elements. Photosynthesis cre- 
ates a characteristic ratio of carbon-12 to carbon-13 
in the organic carbon molecules it produces; the 
ratio differs from the ratio that occurs in inorganic 
sources of carbon. Hence if a rock contains carbon 
at all, a geologist will often measure the ratio of 
carbon-12 to carbon-13 to determine whether the 
source of the carbon is organic or inorganic. 

The Isua rocks, it turns out, contain carbon, ap- 
parently mostly in the form of graphite, which 
is a pure form of the element. The ratio of the two 
carbon isotopes in the graphite suggests that the car- 
bon came from an organic source rather than from, 
say, the ocean or the deep Earth. But we have 
learned from experience that nothing about the Isua 
rocks can be taken for granted. The same metamor- 



44 NATURAL HISTORY May 2004 



phic processes that changed the rocks may also have 
changed the ratios of the two carbon isotopes. 

Still, the carbon-isotope data are the only evi- 
dence so far for the possibiHty of life during Isua 
time. Fragile as the evidence is, geologists are keen 
to know as precisely as possible when that time was. 

Daring the Isua belt is not simple, though, and 
we do not know the ages of all its rocks as precisely 
as we'd like. The belt rests on a substrate of meta- 
morphic rocks of different ages. Those rocks con- 
tain zircons and so are readily dated, but the zircons 
indicate that the substrate rocks are younger than 
the Isua rocks (which, according to uranium-lead 
dating methods, first metamorphosed roughly 3.8 
billion years ago). That inversion of the principle of 
stratigraphic dating — that older rocks should be 
below younger ones — implies that a fault separates 
the Isua belt from the underlying metamorphic 
rocks, and so the latter say nothing about the belt's 
age. Another problem is that the Isua belt appears 
to be made up of at least two, possibly unrelated 
successions of rock layers that were brought into 
contact by movement along faults. 

The most clear-cut way of dating such complex 
rock sequences is to find either zircon-bearing ash 
layers, formed during volcanic eruptions, or struc- 
tures known as dikes, where magma intruded 
along a crack in the rocks. Ash layers are generally 
interleaved with beds of lava and sediment, and so 
a rock that contains such a layer was formed at ap- 
proximately the time of the ash deposition. A 
granite dike, on the other hand, can give only a 
minimum age for the rock that the dike cuts across. 
(After all, the granite magma must have had some- 
thing to intrude into.) The Isua rocks have been so 
severely modified that it is almost impossible to tell 
if a particular unit was an ash layer or a dike that 
just happens to run parallel to the other beds. 
Some dikes and possible ash layers have been found 
in the Isua belt, and they are the main source of 
current chronological knowledge. But in some 
parts of the belt these features are rare, so our team 
in Greenland was looking for previously unnoticed 
dikes and ash layers that could be dated. 

Our expedition to Greenland was a fine ad- 
venture and, incrementally, a scientific suc- 
cess. We did find more old dikes, and returned to 
warmer climes with more zircon-bearing rocks. 

When we began our expedition, all of us knew 
that the Isua rocks are by no means the oldest known 
rocks on Earth, let alone the oldest terrestrial mater- 
ial. The oldest rock discovered so far is from the so- 
called Acasta gneiss, a body made up of a variety of 
granitic rocks of various ages, located in Canada's 



Northwest Territories. The oldest rock in the Acasta 
gneiss, based on the age of its zircon crystals, solidi- 
fied slightly more than 4 billion years ago. 

It probably won't come as a surprise that the old- 
est known terrestrial material is a zircon. The crys- 
tal in question is a fragment just a few thousandths 
of an inch across. It and many other old zircons 
come from metamorphosed sediments deposited in 
river deltas some 3 billion years ago in what is now 
southwestern Australia. The rocks contain a variety 
of old zircons, and several percent of them are older 
than 3.9 billion years. At the corner of one of these 
crystals was the record-setting fragment, aged 4.404 
billion years. Earth itself had formed less than 150 
million years earlier. 

The oldest zircons offer tantaUzing hints about 
the state of that early Earth. The ratios of oxygen 
isotopes in some of the zircons are unlike the ratios 
in the mantle but similar to those occurring in con- 







% 

%^i# 




Zircon crystals, here magnified WO diameters, are typically a 
few thousandths of an inch long. 

tinental crust that formed in the presence of water. 
That finding has led to speculations that the zircons 
formed in magmas derived from continental crust, 
and that water was somewhere present. Water is 
essential for Ufe, and so in principle life could have 
begun on Earth earlier than 3.8 billion years ago. 

But the period from the birth of the Earth, 4.6 
billion years ago, until 3.8 biUion years ago was a 
violent time, richly deserving its name, the Hadean 
era (from "Hades"). At that time our planet was 
constantly bombarded by meteors. Perhaps the 
bombardment accounts for the absence of rocks 
older than about 4 billion years. Litde from the 
Hadean other than zircons — hard, chemically 
durable, subject to growth, and datable — has sur- 
vived for us to behold with wonder; they are our 
main windows into that distant era. D 



May 2004 N.'iTURAL HISTORY 45 



John James Audubon ('1785-185 1) is best known, 
of course, for his exhaustively documented, life-size 
renderings of North American birds. But Audubon 
recorded his meticulous observations in notes and 
journals as well as in his art. His writings show'in 
vivid detail that, less than 200 years ago, the American 
wilderness was inescapable fact, and that Audubon was 
very much a man of his times: frontiersman, husband, 
father of two boys, and, yes, hunter of birds. 

In 1811 he became the proprietor of a general store in 



Henderson, Kentucky, and began to conceive the plan for 
the paintings that woidd become his life's work. Hie time 
seems almost as distant now as the America that Shake- 
speare's Miranda, in The Tempest, called a "brave new 
world. " In his new book, Under a Wild Sky, Williatn 
Souder helps us re-imagine the setting, bhssfully pastoral 
yet at times overwhelmingly violent. Most of the images 
that accompany this article are reproductions of paintings 
by Audubon, depicting some of the birds Souder 
mentions in the text. — The Editors 




Audubon in Kentucky 

The young painter and ornithophile conceived his Ufe's work 
in a country so rich in birds that their flocks blackened the sky. 




By William Souder 



Once, as John James Audubon stalked the 
woods of Kentucky, he found a very 
young turkey cock separated from its 
brood-mates, and brought it home. The bird be- 
came tame and popular with the people of Hen- 
derson, following anyone who spoke to it. The 
turkey grew large, but refused to commune with 
Audubon's domestic turkeys. Every evening it 
could be seen silhouetted against the sky on the 
ridgetop of the Audubon house, the only place it 
would deign to roost. 

Occasionally, the bird would retreat to the forest. 
During one of its disappearances Audubon was out 
hunting, and happened on the animal. He would 
have shot it had his dog not recognized the bird, 
which remained unperturbed while the two 
hunters, man and dog, walked up to it. His wife, 
Lucy, later tied a red ribbon around the bird's neck 
to alert local hunters that it was not a member of the 
wild flock. Nevertheless, it was eventually killed by 
a hunter who didn't see the ribbon untU he picked 
up the dead bird. The man apologetically brought 
the turkey to Audubon, who probably ate it. 

Audubon's determination, however vaguely 
formed in 1811, to survey the natural history 
of American birds was apparent in the attention he 



paid to the behavior and traits of every species he 
encountered. He thought goldfinches and purple 
finches among the smartest birds. Somehow they 
had learned a trick for escaping from "bird lime," a 
sticky substance commonly used to capture small 
birds. When a goldfinch landed on a twig 
Audubon had coated with bird lime, he saw that 
the bird recognized its predicament at once. In- 
stead of struggling, the bird pressed its wings 
against its body and fell backward, causing itself to 
hang upside down. Gradually the glue began to 
give, stretching into a long strand, like the filament 
of a spider's web, until the goldfinch realized it was 
about to break. Then, with a flap of its wings, the 
bird flew off. 

Another of Audubon's favorites was the Ameri- 
can white pelican, which congregated around 
Henderson in the fall. Audubon observed the pel- 
icans in large flocks, sitting on low islands or 
swimming in the river shallows, often packed to- 
gether so densely that he could kill several at a time 
with a single discharge of his gun. Although 
Audubon found all birds beautiful, he considered 
the white pelican unusually handsome, in part be- 
cause of the bird's meticulous grooming habits. He 
was impressed at how different the bird was from 
its cousin, the brown pelican, in the way it fished. 



46 NATURAL HISTORY May 2004 




Wild turkey, perhaps similar to the one Audubon once kept as a pet 



May 2004 NATURAL HISTORY 47 



The white peHcan, he noted, never dives on its 
prey from the air; instead, it swims after the fish 
and sweeps them up by extending its neck and 
thrusting its head underwater. 

Sometimes a flock hunted together in a well- 
choreographed effort. One Indian summer after- 
noon, as the sun lowered in the westerh sky, 
Audubon watched a flock of white pelicans lazing 
about on a sandbar in the Ohio River. Suddenly a 
commotion started up in a smaU bay a little way 
off, and the flock instantly went on alert. The birds 
waddled into the water, where the ungainliness of 
their land movements ceased, and they began to 




Passenger pigeons in flocks could number in the billions, 
according to Audubon's personal observation. Hunting them 
to extinction seemed as likely as emptying the ocean by 
the spoonful. 

glide forward across the current in a surging mass, 
toward the place where a school of small fish had 
begun thrashing the surface. The fish, Audubon 
said, seemed at play. They made the water sparkle. 
As the pelicans approached, the splashing contin- 
ued. The birds swam closer together and, nearing 
the shoal, spread out their wings so that they 
formed a solid wall pushing forward. Now the pel- 
icans propelled themselves faster still, sending the 
fish fleeing ahead, into ever shallower water, herd- 
ing the school toward its demise. When the fish 
were at last trapped against the shore, the peHcans 
moved in, heads lowering, and devoured them by 
the thousands. 

Years later, when he was writing about North 
American birds, Audubon consulted his records 
for the behavioral traits and the descriptions of 
each species, sometimes in conjunction with an 
examination of more recently killed specimens. 



But he relied on memory, too. However far he 
traveled from Kentucky, his days there in its lush 
forests went with him. He could recall how white 
a pelican appeared in the afternoon sun, and how 
cool he felt in the shade of a towering sycamore as 
he leaned against its smooth trunk. He took with 
him the feel of his gun pounding into his shoulder, 
its stock pressed against his cheek. He remembered 
how the stillness of a pallid dawn was split by the 
whistle of wings cutting through the air, some- 
times like a gentle breeze, other times like the 
sound of silk tearing. Long after he left, Audubon 
could still hear the calls and songs that rang 
through the trees, mixing with the sounds of rivers 
and storms and horses. He could feel the puU of a 
swamp against his shins and call to mind the tor- 
ment of mosquitoes and withering heat spells and 
terrible winters when life seemed to stop. Much of 
what Audubon saw and remembered now survives 
only in remnants, and some of it is gone. 

In the fall of 1813, while traveling on horseback 
from Henderson to Louisville, Audubon saw a 
low smudge in the sky. It resembled a dark cloud at 
first, but it pulsed with movement at the edges and 
rapidly grew larger. He heard a rumble, and at 
once the smudge became a surging mass of dark 
points in the sky. A flock of passenger pigeons was 
flying directly toward him. 

The passenger pigeon was a darkly beautiful, 
medium-size bird that looked like a slightly larger 
version of the rock dove — the bird better known 
today as the common city pigeon — only more 
richly colored. Its shoulders, back, and sleek, 
rounded head were slate blue. That coloration 
blended into a deep reddish brown on its chest. 
Seen at a glance, the bird looked purple. 

Today, of course, the passenger pigeon is extinct 
[see "The Face of Extinction," by Hanna Rose Shell, 
page 72] . In its day, though, it was almost certainly 
one of the most abundant bird species that ever 
lived. From the moment European settlers arrived 
in North America, they were awestruck by the in- 
credible numbers of "wild pigeons" that traveled 
in immense groups, ceaselessly traversing the 
continent in search of food. So huge were the 
flocks that they acted more like storm systems than 
assemblages of birds, and they moved with the 
speed and power of hurricanes. 

The flock coming toward Audubon seemed to 
include a great many birds, even by passenger- 
pigeon standards. As he dismounted his horse, he 
began to count what at first seemed to be succes- 
sions of discrete flocks. But he soon lost track, as 
the flocks merged into an endless, indistinguish- 



48 NATURAL HISTORY May 2004 




Passenger pigeons (female, top, and male, above) became extinct in the wild in 1900. 



May 2004 NATURAL HISTORY 49 



able black column across the sky, stretching from 
horizon to horizon. Mounting his horse again and 
moving on, Audubon found the pigeon numbers 
increasing. Although it was midday, the sky dark- 
ened — as if, he later recalled, the sun had been 
eclipsed. Pigeon droppings fell like snow. The 
sound of rushing wings overhead luUed him into 
something Hke a trance. 

He rode on, surprised that not a single bird 
landed or even strayed near the earth. Once he tried 
a rifle shot into the flock, which was far ■ out of 
range of his fowling gun. To his amazement, he 
could not hit a single pigeon or even startle the 
flock with the gun's report. When he reached 
Louisville at the end of the day, the pigeons were 
stiU flying, their ranks undiminished. Near the Ohio 
River the pigeons descended, not alighting but 
merely flying low. Audubon found the riverbanks at 
Louisville "crowded with men and boys incessantly 
shooting." The entire population was "all in arms," 
he said, destroying pigeons by the "multitudes." 
When he went to bed that night the pigeons were 
still flying, the arc of the great flock spanning the 
sky. The next morning, they were still passing over- 
head. So it went for three consecutive days, with no 
pause as the birds streamed past. Nobody in 
Louisville could talk of anything else. Everyone ate 
pigeon meat all day. The air smeUed of pigeons. 

Some years after seeing the big flock in Kentucky, 
Audubon made a series of ingenious observa- 
tions about passenger pigeons that probably consti- 
tute as good a description of the species as anyone 
will ever have. Audubon, who sometimes dissected 
birds and sketched their internal organs, determined 
that passenger pigeons completely digested their 
food in about twelve hours. He also learned that pi- 
geons killed in New York were sometimes full of 
undigested rice. Because rice grew only as far north 
as the Carohnas, Audubon was able to make a rough 
calculation of the birds' sustained speed. To arrive in 
New York with rice stiU in their crops, he figured, 
the pigeons would have to maintain an average 
speed of about a rrdle a minute. 

Audubon could now estimate how many birds 
might assemble into a "typical" flock. If you knew 
how fast they flew, he reasoned, you could figure 
the size of the flock. Imagine a column of passen- 
ger pigeons one rrdle wide — a modest premise, he 
said. Now assume the flock passes overhead in three 
hours: that, too, would be conservative. If the birds 
were flying at sixty miles an hour, the entire flock 
could be visualized as occupying a rectangular area 
a mile wide and three-times-sixty miles long: 180 
square miles. Assuming a density of two birds per 



square yard, Audubon concluded that the number 
of birds in his 1 SO-square-mile "layer" of pigeons 
was roughly 1.1 billion. If Audubon's estimates 
were even close to the truth, the big flock he ob- 
served to take three days passing over Kentucky 
might have numbered more than 25 billion birds. 

The passenger pigeon seems to have been a force 
of nature that even the sometimes imaginative 
Audubon was unable to exaggerate. When a flock 
of passenger pigeons dropped out of the sky to 
feed, great havoc ensued. The birds denuded and 
destroyed large sections of forest, and when a flock's 
presence was discovered, people would travel firom 
far away to harvest the birds by the thousands. 

Once, near the Green River in Kentucky, 
Audubon happened upon such a killing 
field. It was in a stand of old forest, with little un- 
derstory, where a flock of pigeons had come to 
roost each night after foraging in the area by day. 
Audubon arrived on the scene about two weeks 
after the birds' first appearance. He found a section 
of forest three miles wide and nearly forty miles 
long, littered with broken branches and Umbs that 
had sheared ofl" beneath the weight of the birds. 
Some trees as wide as two feet in diameter were 
broken ofi'just above ground level. 

Dispersed across this devastated landscape was a 
band of hunters and farmers armed with guns and 
long poles. Wagons were parked in Unes, waiting to 
carry away the spoils of the imminent hunt; some of 
the farmers had brought their hogs to feast on 
freshly killed birds. As the afternoon wore on, de- 
bris was piled into pyres, to be set afire after dark. 
The piles were augmented with smudge pots fJled 
with sulfur, and torches made from tarry pine knots. 

The sun set and the sky went black. At last 
Audubon heard the cry: "Here they come!" With a 
deafening roar of wings, a torrent of pigeons poured 
into the forest, searching for places to alight. Soon 
what remained of the trees filled with birds. The 
flock was so thick they seemed to land on top of 
one another, their dark forms congealing into 
throbbing masses that rocked precariously above the 
earth until the Hmbs beneath them splintered, gave 
way, and came crashing dovwi. Everything below 
was swept away, and the forest floor became car- 
peted with a tangle of fallen and crushed birds. 

The fires and torches were lit. An evil hght fdled 
the woods. The air was acrid and thick with 
smoke; pigeons flew in all directions, passing and 
repassing through their own shadows. People 
flayed at the birds with poles, knocking them 
down by the hundreds. As men began firing into 
the flock, the chaos was so overwhelming that 



50 NATURAL HISTORY May 2004 




American white pelican was one of the handsomest of birds, according to Audubon, not least 
because of its fastidious grooming habits. 



May 2004 NATURAL HISTORY 51 



Audubon could not even hear the reports of their 
guns. Appalled yet transfixed by the scene, he re- 
minded himself that the populations of these birds 
could quadruple in a single breeding season. 

In fact, Audubon thought it inconceivable that 
hunting — even the kind of slaughter he had wit- 
nessed at the Green River — could diminish the 
numbers of passenger pigeons. Only the continued 
clearing of the North American forest, he thought, 
could threaten this remarkable bird, which seemed 
to him a mobile but permanent part of the Ameri- 
can landscape. 

Populations of animals that go extinct typically 
shrink to very small numbers before vanishing, 
as isolated groups and then individuals are wiped 
out one by one. Usually the 
process is a natural one. A 
typical species persists about 
a million years on earth, and 
many more species have al- 
ready gone extinct than exist 
today. But the passenger 
pigeon lived in huge num- 
bers right up to the time it 
went very suddenly extinct. 
Ornithologists now think 
the species was adapted to 
survive and breed only in 
massive flocks of iTuUions 
upon millions of individuals. 
Even when many remained, 
there were not enough. 

Another American icon 
of Audubon's day, the Car- 
olina parakeet — or parrot, 
as it was also known — met 
much the same fate. The 
Carolina parakeet was al- 
ready in decline when 
Audubon began observing 
it in Kentucky, though its 
numbers were still so great 
in the early nineteenth 

century that the bird was seen in immense flocks 
across much of eastern North America. Yet, like 
the passenger pigeon, the CaroHna parakeet would 
be gone in less than a century — disappearing in 
defiance of the usual precondition for extinction, 
which is rarity. The last time anyone saw a passen- 
ger pigeon in the wild was in 1900. The Carolina 
parakeet disappeared from the wild five years later. 
The very last individuals of both species died in 
zoos not long thereafter. 

Loss of habitat and a great continuing slaughter — 




Carolina parakeet, a pest to farmers and an easy 
target for hunters, became extinct in the wild in 
1905, a victim of the gun and the loss of its home. 



by hunters seeking to supply a market hungry for 
the Carolina parakeet's extravagant feathers, and by 
farmers trying to save their crops from marauding 
flocks — devastated a magnificent species that many 
regarded as a pest. Audubon, whose published 
drawing of the Carolina parakeet was done firom 
specimens he shot in Louisiana, wrote that these 
birds were fond of cockleburs, the small, spiny fruit 
that is found plentifully — perhaps, as a prickly 
Audubon noted, "much too plentifully" — across 
the eastern and southern parts of America. 

The problem for the parakeet, Audubon said, 
was that it also loved nearly every kind of fruit and 
grain "indiscriminately." Corn was just about the 
only farm crop it wouldn't eat. A flock of CaroHna 
parakeets — think of a roiling, deep-green ocean 
falling out of the sky — 
could lay ■waste to a large 
area of cropland. When 
feeding, the birds were 
oblivious to their sur- 
roundings and easily ap- 
proached. Even after being 
shot at, they remained easy 
targets. Younger parakeets, 
Audubon reported, were 
"tolerable" table fare. But 
mainly the birds were shot 
just to get rid of them. 

Carolina parakeets issued 
a sharp, screeching call — a 
"scream" to Audubon's 
ears — that was hard to abide 
at close range. Although 
they could be tamed by 
being repeatedly dunked 
in water — a lamentable 
practice with which Audu- 
bon was evidently famil- 
iar — they could not mimic 
human speech and never 
gave up their own call. To 
the man who made a pet 
of a turkey and became 
virtually the American patron saint of all things 
ornithological, Carolina parakeets were still "so 
disagreeable as to render them at best very in- 
different companions." The bird was wild and 
destined to stay that way, but, like Audubon's 
recollections of his younger years in the back- 
woods, only as a memory. D 

Aiiapted from Under a Wild Sky: John James Audubon and the 
Making of The Birds of America, by Willium Souder, to be published 
in June by North Point Press, a division ofFarrnr, Straus and Giroux, 
LLC. Copyright ©2004 by William Soiider All rights reserved. 



52 NATURAL HISTORY May 2004 



REVIEW 







Stephan Balkenhol, Hybrids, 1995 



Brains and the Beast 

Can the hehaviorist's insistence on distinguishing animal 
from human cognition he reconciled with evolutionary continuity? 

By Frans B. M. de Waal 



If your dog drops a tennis ball in 
front of you and looks up at you 
with tail wagging, do you figure 
she wants to play? How naive! Who 
says dogs have desires and intentions? 
Her behavior is merely the product ot 
reinforcement: she has been rewarded 
for it in the past. 

Many scientists have grown up with 
the so-called law of effect, the idea that 
all behavior is conditioned by reward 
and punishment. This principle ot 
learning was advocated by a dominant 
school of twentieth-century psycho- 
logical thought known as American 
behaviorism. The school's founders, 
John B. Watson and B. F. Skinner, were 
happy to explain all conceivable be- 
havior within the narrow confines of 
what Skinner called "operant condi- 
tioning." The mind, if such a thing 



even existed, remained a black box. In 
the early days, the behaviorists applied 
their doctrine m equal measure to 
people and other animals. Watson, tor 
instance, to demonstrate the power of 
his methods, intentionally created a 
phobia for furry objects in a human 
baby. Initially "little Albert" was un- 



Do Animals Think? 

by Clii'c D.L. Wynne 

Princeton University Press, 2004; 

$26.95 

Intelligence of Apes 
and Other Rational Beings 

by Duane M. Rwnbaugh 

and David A. Washburn 

Yale University Press, 2003; S3 5. 00 



afraid of a tame white rat. But atter 
Watson paired each appearance of the 
rat with sharp noises right behind poor 
Albert's head, fear of rats was the in- 
evitable outcome. Even human speech 
was thought to be the product of sim- 
ple reinforcement learning. 

The behaviorists' goal of unifying 
the science of behavior was a noble 
one — but alas, outside academia the 
masses resisted. They stubbornly re- 
fused to accept that their own beha\'ior 
could be explained without consider- 
ing thoughts, feelings, and intentions. 
Don't we all have mental Uves, don't 
we look into the future, aren't we ra- 
tional beings? Eventually, the behaidor- 
ists caved in and exempted the bipedal 
ape from their theors' of e\'er\'thing. 

That was the beginning of the 
problem for other animals. Once cog- 



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nitive complexity was admitted in 
people, the rest of the animal king- 
dom became the sole standard-bearer 
of behaviorism. Animals were ex- 
pected to follow the law of effect to 
the letter, and anyone who thought 
ditTerently was just being anthropo- 
morphic. From a unified science, be- 
haviorism had become a dichotomous 
one, with two separate languages: one 
for human behavior, another for ani- 
mal behavior. Human rationality and 
superiority are not really the issue, 
however — one only needs to read the 
latest Darwin Awards to notice that 
our species can be less rational than 
advertised. The issue is the dividing 
line between us and the rest of nature. 
Radical behaviorists adamantly insist 
on this Hne, and look across it with en- 



This story sets the tone of doubt and 
reserve that permeates the book. 
Wynne includes numerous insightful 
accounts of remarkable animal be- 
havior, but he invariably concludes on 
a note ot caution: one should not 
infer too much fi-om these accounts. 
He is not so radical a behaviorist that 
he excludes all forms of reasoning by 
animals, but he takes greater pleasure 
in explaining what animals cannot 
do — ^monkeys fail to understand rela- 
tions bet\veen cause and effect, apes 
can sign but lack the syntax that defines 
human language — than in describing 
what they avi do. Capacities unique to 
a particular species, such as echoloca- 
tion in bats, get Wynnes fLJl admira- 
tion. But anything that seems to elevate 
other animals close to the lofty cogni- 



Fifty years ago a female macaque began 
washing sweet potatoes before eating them; 
now her entire group has picked up the practice. 



tirely different eyes than the ones they 
reserve for their fellow human beings. 
They speak about animals as "them" 
and compare "them" with "us," as 
CHve D. L. Wynne does at the begin- 
ning of Dd Animals Tliink? ("What are 
animals — really? What should we 
make of them?"). Other behaviorists, 
however, intentionally blur the line. 
They apply the same well-tested be- 
haviorist methodology to reconnect 
human and animal behavior, daring to 
mention the words "animal" and 
"cognition" in the same breath. They 
write books such as Duane M. Rum- 
baugh and David A. Washburn's Intelli- 
gence of Apes and Other Rational Beings. 

Of the two, Wynnes book is by far 
the more readable. Wynne has a 
pleasant writing style and a knack for 
engaging the reader. He begins with 
the story of a mad animal-rights activist 
who threatened the Uves of people on 
the Isle of Wight, where Wynne grew 
up. The man was convinced that ani- 
mals are sentient beings, a certainty 
Wynne says he wishes he could share. 



tive level of humankind he regards with 
utmost skepticism. He seems to take 
delight in animals, and possesses great 
knowledge about them, yet he prefers 
them at arm's length. The constant 
message is that animals are not people. 

That much is obvious. But it is 
equally true that people are animals. 
The dichotomy Wynne advocates is 
outdated, lending his book a pre- 
Darwinian flavor. Take the case of an- 
imal culture, currently one of the 
hottest areas in the study of animal 
behavior. The idea goes back to the 
pioneering work of Kinji Imanishi, 
who proposed in 1952 that if individ- 
uals learn from one another, their be- 
havior may grow so different from 
behavior in other groups of the same 
species that they seem to have their 
own culture. Imanishi thus reduced 
the idea of culture to its most basic 
feature: the social rather than the ge- 
netic transmission of behavior. 

Many examples of animal culture 
have been documented. The classic 
case emerged among wild macaques 
on Japan's Koshima Island. During 



their fieldwork with the monkeys 
there, investigators provisioned them 
with sweet potatoes, which a juvenile 
female named Imo soon began wash- 
ing; she would bring her potatoes to a 
small river and clean them off before 
eating them. Imo's washing behavior 
spread first to her mother and then to 
her age peers, before atTecting the rest 
of the group. Later Imo moved her 
operation to the shoreline, washing 
the potatoes in the ocean, and, again, 
the other monkeys followed. 

Some psychologists have objected 
to this example, pointing out that it 
is uncertain whether the monkeys 
learned their skill by copying others or 
by discovering the behavior individu- 
ally, without anyone's help. Wynne 
supports the second view. But instead 
of basing his opinion on the actual 
data published by a team of Japanese 
primatologists, who have worked on 
the problem for fifty years, he relies on 
the word of a skeptical Westerner who 
has never set foot on the island. This 
scientist, a speciahst in rat behavior, 
suggested that potato washing spread 
because performers were selectively 
rewarded by the people who handed 
out the potatoes. 

A few years ago I went to Koshima 
Island to verify the idea of selec- 
tive rewarding. I talked with some of 
the people who had actually witnessed 
Imo cleaning her first spud. They told 
me that initially the monkeys were fed 
far away from any water, so there was 
no question of rewarding any washing 
behavior. Imo herself came up with the 
idea of transporting the potatoes to the 
river for cleaning. They also pointed 
out that one cannot feed a group of 
monkeys any way one wishes. The 
dominant males have to be fed first, 
the females second, and the little ones 
last; changing the order sparks blood- 
shed. Thus, except for Imo's mother, 
the monkeys that learned the behavior 
first, the juveniles, were the last to be 
rewarded. In fact, the only monkeys 
on the island that never learned potato 
washing were the adult males; pre- 
cisely the best-rewarded group. 



Wynne invariably fwors interpre- 
tations that widen the assumed cogni- 
tive gap between human and animal. 
For example, he uncritically accepts 
the uniqueness claim dn jour: that 
only human beings possess a theory ot 
mind (ToM), or the cognitive ability 
to understand that others, too, have 
mental states such as thoughts and 
knowledge. Ironically — given Wynne's 
dismissal of an ape ToM — the concept 
got its start with a 1970s study of 
chimpanzees. A female showed she 
had grasped the intentions of others 
by, for example, selecting a key from 
among several tools if she saw a person 
struggling to open a locked door. 

Evidence for a theory of mind in 
apes has gone through its ups and 
downs ever since. Some experiments 
have failed spectacularly, leading the 
proponents of one school of thought 
to contend that apes simply lack the 
capacity. Negative results are incon- 
clusive, though: as the saying goes, ab- 
sence of evidence is not evidence of 
absence. Furthermore, the perform- 
ance of apes is often assessed by com- 
paring it with that of children. Be- 
cause the experimenter is invariably 
human, however, only the apes face a 
species barrier. When an ingenious 
experiment conducted at Emory Uni- 
versity's Yerkes National Primate Re- 
search Center in Atlanta got around 
that problem, the evidence for an ape 
ToM was more positive; chimpanzees 
seemed to realize that if a member of 
their species had seen hidden food, 
this individual knew where the food 
was, as opposed to one who had not 
seen it. That finding threw the ques- 
tion of a ToM in nonhuman animals 
wide open again. 

In an unexpected twist (because 
the debate has focused on humans 
versus apes), a capuchin monkey in a 
laboratory at Kyoto University in 
Japan recently passed a series of see- 
ing-knowing tasks with flying colors. 
The least one can conclude is that it is 
premature to settle on ToM capabili- 
ties as the ultimate Rubicon. 

In spite of Wynne's dismissal of an 
ape ToM, his book offers many in- 

May 2004 NATURAL HISTORY 55 



EVOLVING 
NATURE 








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Diversity, Gender, and Sexualit)' 
in Nature and People 
by Joan Roughgarden 
"An entrancing tale of sexual ambiguit)- 
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written from the heart." 

— Stevi Jones, author of Danvin's Ghost 

BEASTS OF EDEN 

Walking Whales, Dawn Horses, 

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At bookstores or order 
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UNIVERSITY OF 
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sightful descriptions of animal behav- 
ior. A wonderful chapter on the role 
of messenger pigeons during the Fn-st 
World War includes a picture of the 
stuffed body of .Cher Ami, a genuine 
war hero. The pigeon kept flying 
after its leg had been shot off, deliv- 
ering its message and thus rescuing an 
entire battalion. 

Rumbaugh and Washburn are 
considerably more open-minded 
about the mental accomplishments of 
animals than Wynne is. Their book 
celebrates Rumbaugh s lifetime of re- 
search on monkeys and apes. In fact, 
what fascinates me the most about 
Intelligence of Apes and Other Rational 
Beings is its historical overview of 
experimental work with pri- 
mates, first with the Wisconsin 
General Testing Apparatus 
(WGTA) and later with joy- 
sticks and computers. 

The WGTA was developed at 
the University of Wisconsin in 
the 1940s, and is still being used 
today. In this set-up, a primate 
subject in a cage faces an experi- 
menter across a platform, on 
which differently shaped or col- 
ored stimuli are arrayed. Both 
experimenter and primate can 
reach the stimuli; the experi- 
menter baits them with rewards, 
and the primate selects among 
them. I remember working with Steph 
such an apparatus as a student, 
testing chimpanzees to see if they could 
discriminate shapes by touch alone. 
The task was so incredibly simple and 
repetirive that the apes invariably got 
tired of the whole thing five ininutes 
into the testing. In fact, they got so 
bored that they performed worse than 
macaques tested on the same stimuli. 

I mention this episode because test 
performance is often taken as a mea- 
sure of intelligence, even though at- 
tention and motivation are equally 
important to the outcome. As a result, 
failure is open to interpretation. 
Rumbaugh and Washburn understand 
these points better than most scien- 
tists, and they are at pains to remind 



the reader how the questions one asks 
tend to constrain the answers one gets. 
Indeed, some testing paradigms 
positively suppress the phenomena 
being tested. When Rumbaugh re- 
placed the WGTA with an innovative 
testing setup in which the monkeys 
move a joystick to select stimuH on 
a computer screen, their performance 
improved dramatically. Rumbaugh's 
work on the connection between 
method and outcome should be re- 
quired reading for anyone who attaches 
significance to negative evidence. 

One learning paradigm discussed 
by Rumbaugh and Washburn 
has special interest. Some animals learn 
how to learn — that is, once they have 




an Balkenhol, Man with Lions, 1994 

mastered a particular task, they can 
more quickly learn future tasks that 
have the same design but rely on dif- 
ferent stimuli. Trial-and-error learning 
cannot explain improved performance 
in reaction to new stimuU, hence the 
level of learning must be higher. But 
generalization across tasks is precisely 
what the founders of behaviorism 
thought animals could not do. 

Rumbaugh and Washburn discuss 
many forms of advanced problem- 
solving, which they classify as "emer- 
gents." The term is sHghtly awkward, 
but the authors apply it to cases in 
which animals flexibly apply accumu- 
lated knowledge to new situations, re- 



sulting in an "emergent" solution. 
The classic example is the chimpanzee 
in a room with a few sticks and boxes 
in one corner and, for the first time in 
the chimp's experience, a banana 
hanging from the ceiling. The solu- 
tion emerges as the old bits of previ- 
ous knowledge combine until, as if a 
lightbulb suddenly goes on in the 
chimpanzee's head, he cHmbs on top 
of the boxes and reaches for the ba- 
nana with a stick. 

The two authors rightly speak of 
reasoning and rationaUty, and so adopt 
a terminology that is anathema to 
radical behaviorism. They discuss the 
behaviorist view at length but choose 
to deviate from it, stressing continuity 
between animal and human. For the 
reader, though, it is firustrating 
that they focus almost entirely 
on apes and other primates, 
without examining how the 
concept of emergents could 
apply equally well to other an- 
imals. Crows, dolphins, ele- 
phants, and parrots have been 
credited with creative problem- 
solving as well. 

There will always be tension 
between those who view 
animals as only slightly more 
flexible than machines and those 
who see them as only slighdy less 
rational than human beings. The 
views discussed in these two 
books are by no means as far 
apart as they could be; both, after all, 
come out of the same tradition of ex- 
perimental psychology. Throw in a few 
naturalists and neuroscientists, and the 
debate gets even more complex. That 
said, however, the two books range 
widely enough across the spectrum of 
views to make a powerful case that 
there is still plenty to be discovered, 
and that human uniqueness is largely in 
the eye of the beholder. 

Frans B.M. de Waal is C.H. Candler 
Professor of Primate Behavior at Emory Uni- 
I'crsily in Atlanta and the director of the Liv- 
ing Links Center at the iifiii'ersity's Yerkes 
National Primate Research Center 



56 NATURAL HISTORY t^ ay 2004 



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BOOKSHELF 



By Laurence A. Marschall 



Rats: Observations on the History 

and Habitat of the City's 

Most Unwanted Inhabitants 

by Robert Sullivan 
Bloonishury, 2004; $23.95 



In his memorable 1998 book The 
Mcadou'lands, about the New Jersey 
wetlands just west of the Lincoln Tun- 
nel, Robert Sullivan emerged as the 
Thoreau of blighted ecosystems. Trav- 
eling by canoe along oil-slicked bayous, 
Sullivan uncovered treasures of both 
natural and industrial history no passing 
commuter would have suspected. 

Now Sullivan has crossed the Hud- 
son River and relocated his eclectic 
wanderings to the back alleys of lower 




Rattus norvegicus: urban success story 

Manhattan, where the dumpsters of 
Chinese noodle joints, Irish pubs, and 
Salvadoran chicken takeouts are the 
real happening places for urban wild- 
life. Happening, that is, if you're a rat. 
"Four seasons spent among vermin" 
is how Sullivan describes his sojourn. 
His Walden Pond was Edens Alley, a 
narrow defile a few blocks from WaU 
Street. Equipped with both binoculars 
and a night-vision monocular, he ar- 
rived in the evenings after dark to 
watch the rats as they emerged to feed 
and, in the notebook he'd brought 
along, to wax lyrical about nature, civ- 
ilization, and the nieamng of hfe. A 
typical entry from his winter journal: 

5:44 — The rats retreat suddenly. The rea- 
son: three men enter the alley, though 
when I see the men I wonder which crea- 
ture left the allev for which creature — 



sometimes it seems as if the rats' departure 
is a courtesy extended by the rats. ... I 
think of all the rats that have crawled 
through this alley before, the history of this 
alley's previous inhabitants. Oh, to 
know — to really know — this pelHcle of 
rat-infested ground. 

Such deadpan effusiveness over 
creatures commonly regarded as loath- 
some may border on sick humor, but 
elegies to Rattus norveg^kiis make up 
only a small part of SuUivan's book. 
There are many stories about the 
ethology, natural history, and social 
importance of rats, and, overaD, plenty 
of evidence that people and rats have a 
lot more in common than most people 
would Uke to admit. 

Sullivan cites Martin W. Schein, for 
instance, the co-author of a 1953 
paper on the eating habits of rats 
captured on Baltimore backstreets. 
Schein conducted laboratory studies 
using authentic garbage from the al- 
leys where the rats were trapped. He 
learned that rats hate raw beets (I 
sympathize) and that scrambled eggs 
and macaroni and cheese are popular 
rat comfort foods, just as they are for 
human Baltimoreans. In Edens Alley, 
according to Sullivan, the rats also 
seem to like chicken pot pie. 

In spite of some strong dislikes, 
though, rats are not picky eaters. By 
and large, they are omnivorous and 
highly adaptable — the same traits that 
make people so successful — and they 
show uncanny cleverness in finding 
food and avoiding peril. Ann Li, an 
epidemiologist with the New York 
City Department of Health, takes 
Sullivan on a rat-trapping expedition 
to Brooklyn, and tells him she thinks 
rats are "so underappreciated." Even 
the exterminators who show Sullivan 
how to outsmart the rodents express a 
grudging admiration for their prey. 

As much as he shares the roden- 
tophilia of his informants, Sullivan is 
unsparing when he recounts the mis- 
ery rats cause. Sometimes they attack 
directly: in 1979 a large pack sur- 
rounded a woman on a street in down- 
town Manhattan. And of course they 



cari-y infectious diseases such as plague. 
Yet unless people find a way to steam- 
clean each crevice of the city every 
day, rats will continue to cohabit with 
us in uneasy harmony. "If you killed 
every rat in New York City," Ann Li 
remarks, "you would have created new 
housing for 60 million rats." 



Running ivith Reindeer: 
Encounters in Russian Lapland 

by Roger Took 
Westuiew Press, 2004; $27.50 



Few places in Europe are as far off 
the beaten track as the Kola 
Peninsula, a potato-shaped carbuncle 
of land at the top of the Scandinavian 
Peninsula, east of Finland. Russian 
Lapland, as the Kola is also known, has 
one large city (Murmansk), a few sub- 
sidiary industrial centers and mining 
towns, and a scattering of isolated vil- 
lages in the hinterlands. One passable 
highway runs through the province. 
But beyond that right-of-way, for 
hundreds of kilometers in every direc- 
tion, the hardy traveler encounters 
nothing but tundra, taiga (boreal for- 
est), and vacant shoreline. 

Roger Took is just such a hardy 
traveler — perhaps even a foolhardy 
one. When he arrived in the Russian 
nortliland in the early 1990s, the en- 
tire country was teetering on the edge 
of anarchy, and it was not clear which 
disaffected group a lone Englishman 
should be more afraid of suspicious 
Sami tribesmen, the mihtary attached 
to the remnants of the Russian 
Northern Fleet, or the legendary 
Russian Mafia. Just in case. Took 
offhandedly notes, he learned how to 
fire, strip, and reassemble a nine-mil- 
limeter semiautomatic pistol before he 
left London. 

We never learn whether Took ever 
fired the pistol, but readers can be 
grateful that he survived, met many 
hiscinating characters, and kept com- 
ing back, year after year, for more than 
a decade. The Kola, he discovered, is a 



58 NATURAL HISTORY May 2004 



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TASMANIAN TIGER 

THE TRAGIC TALE OF HOW THE WORLD LOST 
ITS MOST MYSTERIOUS PREDATOR 

DAVID OWEN 

"Why would anyone want to read a book 

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humanity's relentless arrogance in the face 

of a world of wonder, the tragic fate of 

which is a warning for us all." 

RICHARD FLANAGAN 
author ot Gciihl's Book of Fisli 

S25.iin h.irdcover 

THE JOHNS HOPKINS UNIVERSITY PRESS 

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little more than a backpack and a fish- 
ing rod, he boldly wandered through 
military reservations, floated down 
rivers with salmon poachers, sledged 
to hunting and herding excursions 
with descendants of the Sami, and ac- 
companied wildlife biologists and ar- 
chaeologists on expeditions to the in- 
terior. In one memorable episode he 
hitched a ride through the backcoun- 
try on a clanking, tanklike all-terrain 
vehicle (minus the gun turret), ac- 
companying a human-rights activist 
who was documenting a gulag of 
prison barracks. 

Took reports signs of a new life for 
Russian Lapland. Environmentalists in 
Russia and Scandinavia have begun to 
throw their weight behind efforts to 
clean up the damage caused by the 
nuclear fleet. Shops in Murmansk 
now display the latest fashions. And 
foreign sportsmen have begun to dis- 
cover that some of the world's greatest 
salmon streams run through the Kola's 
remote countryside. Russian Lapland 
may not come off as a vacation par- 
adise, but Took's book is a marvelous 
introduction to a region of rich but 
almost forgotten heritage. 



Sequoia:Tlie Heralded Tree 
in American Art and Culture 

by Lori Veiinaas 
Siiiitlisonian Books, 2003; $39.95 



Just as Lebanon is famous for its 
cedars, so North America is known 
tor its redwoods. Not only are they 
among the largest and most stately 
trees on earth, but they thrive in set- 
tings of surpassing scenic beauty. 
Strolling beneath a towering canopy of 
Sequoia sempervirens, the most common 
redwood along the northern coast of 
California, one experiences a world of 
subde twiUght just a few steps from the 
glare of a sunlit, rocky shoreline. The 
rarer Sequoiadeudron gigiinteiiiii, whose 
ponderous trunks make their coastal 
cousins seem almost willowy, grow 
farther inland, in sheltered groves in 
Yosemite and other isolated valleys. 
It is no wonder, then, that the giant 



sequoias have assumed symbolic im- 
portance far out of proportion to their 
restricted habitat. Lori Vermaas, a cul- 
tural historian, has written an insightful 
new survey of American art and Litera- 
ture on redwoods from the nineteenth 
and early twentieth centuries. 

The most widespread early depic- 
tions of the giant trees, in the years 
during and just after the Civil War, 
were made by enterprising commer- 
cial artists who used twin lenses on 
their cameras to create so-called 
stereo-view cards. Many of the pic- 
tures focused on the immense scale of 
the trees; a favorite subject was the 
Grizzly Giant, a tree in Yosemite Na- 
tional Park whose trunk soared straight 




Coastal redwood (Sequoia sempervirens) 

skyward but whose upper branches 
seemed painfully gnarled, like the 
rheumatic joints of an old man. 

To a nation still smarting from the 
horrible conflict between the 
states, the redwoods, far removed fi-om 
the scene of battle, seemed serene, im- 
passive, and impervious to harm. They 
epitomized the part of the nation that 
had remained intact and functional de- 
spite the fires of war and social tur- 
moil. Huge paintings of sequoias by 
such landscape artists as Albert Bier- 
stadt were all the rage (oversize land- 



Hi 



scape paintings being the functional 
equivalents of IMAX films). 

Yet few envisioned the giant trees as 
symbols of an endangered environ- 
ment. Toward the end of the nine- 
teenth century, logging them was even 
seen as an example of humankind's 
ability to bend nature to its will. 
Woodsmen were "no puny imperson- 
ations of men," but men who swung 
"heavy, keen-edged axes as though 
they were mere trifles." Logging teams 
were typically photographed in the 
yawning notches of trees they were 
about to topple. In one particularly 
striking print, an entire troop ot U.S. 
cavalrymen, mounted on horseback, 
stand Uke conquering gladiators atop 
and along the length of the trunk ot a 
fallen giant. 

Exuberantly expansive, the Ameri- 
can imagination invoked sequoias as a 
natural treasure, but a treasure to be 
expropriated and spent. Even John 
Muir, one of the nation's first conser- 
vationists, waxed enthusiastic over the 
use of redwood lumber in construc- 
tion. Redwood housing was "almost 
absolutely unperishable." 

The onslaught of logging opera- 
tions, among other abuses of the era, 
sparked the modern environmental 
movement, and redwoods came to be 
seen as treasures to preserve. Although 
groves of redwoods are continually 
threatened, the trees still stand, and 
pictoriaUsts in the tradition of Ansel 
Adams have continued to use the 
image of the redwood as an emblem 
of strength and endurance. Vermaas 
helps us understand the symbolism of 
sequoias, but even she must admit that 
the best way to appreciate them is on 
foot and close-up. "No one has ever 
successfuDy painted or photographed 
a redwood tree," wrote John Stein- 
beck in 1962. "The feeUng they pro- 
duce is not transferable." 



Laurence A. Marschall, author of The 
Supernova Story, is the W.K.T. Salmi pro- 
fessor of physics at Gettysburg College in 
Pennsylvania, and director of Project CLEA, 
which produces widely used sinuilation soft- 
ware for education in astronomy. 



nature.net 



Moving Mountains 

By Robert Anderson 

Cahfornia's Santa Monica Moun- 
tains, where I Uve, are a mere 
5 million years old. Like most 
mountains, they are comprised of 
rocks formed during complex and 
repeated sequences of uplift, sedi- 
mentation, and volcanism [see "A 
Birthstone for Earth," by Edinond A. 
Mathez, page 40] . In the case of the 
Santa Monica range, the process 
began about 200 million years ago, 
when the first dinosaurs were roam- 
ing the planet. 

A summary of the processes that 
make mountains rise can be found at 
www.physicalgeography.net, a Web site 
created by Michael J. Pidwirny, a 
geographer at Okanagan University 
College in Kelowna, British Colum- 
bia. (On the home page click on 
"Fundamentals: Online Textbook" 
from the menu bar at the top; in 
"Chapter 10: Introduction to the 
Lithosphere," click on "Mountain 
Building.") For an overall view of 
how colliding tectonic plates trans- 
form the planet, go to "Dynamic 
Earth" (earth.leeds.ac.uk/dynamic 
earth), developed by Robert Butler, a 
geologist at the University of Leeds. 

Illustrations of the way tectonics 
has changed the distribution of land 
and sea can also be found at a Web 
site run by Christopher R. Scotese, 
a geologist at the University of 
Texas at Arlington. For thirty years, 
Scotese and his collaborators have 
been working on a series of paleo- 
geographic atlases. The latest of 
them, the Global Plate Tectonic 
Model, is available at "PALEOMAP 
Project" (www.scotese.com). From the 
hoine page you can choose 3-D 
movable paleoglobes and paleogeo- 
graphic animations that show the 
positions of the continents and the 



shapes of the ocean basins for vari- 
ous periods of geological time. Se- 
lect "Earth History" from the menu 
at the left on the home page. There 
you'll find full-color maps depicting 
details such as mountain ranges, 
shorelines, and active plate bound- 
aries during those same periods — 
beginning with the breakup of the 
first supercontinent, Rodinia, and 
extending through the present and 
into the future for 250 million 
years, when the supercontinent 
Pangea Ultima will trap what is 
now the Atlantic Ocean in a small, 
inland basin. 

Antonio Schettino, a geologist 
in Milan, Italy, worked with 
Scotese to re-create plate motions in 
the Mediterranean region (www. 
itis-molinari.mi.it/lntro-Med.html). 
The accompanying QuickTime 
animation provides an excellent 
graphic explanation of how the Alps 
arose. A similar presentation of tec- 
tonic processes shows the ancient 
mountain chains in greater regional 
detail (www4.nau.edu/geology). CHck 
on "Popular Departmental Links" 
and look at the three items created 
by Ronald C. Blakey, a geologist at 
Northern Arizona University. The 
site www.jamestown-ri.info/northern_ 
appalachians.htm provides a rundown 
of the northern Appalachian chain's 
geological history, which stretches 
back a biUion years. 

Geologists can now watch 
mountains grow, thanks to new- 
satellite and radar technologies 
that measure minute movements 
of the Earth's crust and slight 
changes in the stresses that cause 
earthquakes. Go to the "Active 
Tectonics" site, run by a group 
from the University of Calitornia, 
Berkeley (www.seismo.berkeley.edu/ 
-burgmann/EDUCATION/inSAR.html), 
for more information. 

Robert Anderson is a freelance science 
writer living in Los Angeles. 



tVlay 2004 NATUR.^L HISTORY 63 



OUT THERE 



Too Many X Rays 

In a sky visible only from outer space, astronomers may have 
found the first example of an intermediate-size black hole. 



By Charles Liu 

Astronomers possess X-ray vi- 
sion, even tliough none of 
my colleagues, to my knowl- 
edge, hails from the planet Krypton. 
Telescopes designed to collect and 
focus X rays from space provide that 
vision. X rays are highly energetic — 
that's why they so readily penetrate 
matter — and so an X-ray telescope 
offers the chance to observe cosmic 
phenomena powerful enough to gen- 
erate highly energetic radiation. 

In the past four decades a succes- 
sion of orbiting X-ray telescopes has 
opened up the high-energy X-ray 
window on the universe to eager as- 
tronomers. Today, two X-ray obser- 
vatories shoulder most of the load: 
Chandra, run primarily by NASA; 
. and XMM-Newton, managed by the 
European Space Agency. 

Among the most puzzHng denizens 
of the X-ray sky are the so-called ultra- 
luminous X-ray sources, or ULXs. 
The objects generate so much X-ray 
flux that they seem to violate the laws 
of physics. They don't, of course — so 
what is it that supercharges then- X-ray 
power? A recent study led by Luca 
Zampieri of the Astronomical Observ- 
atory in Padua, Italy, suggests an in- 
triguing candidate: a black hole several 
hundred times the mass of the Sun that 
drags matter from an orbiting star and 
then converts that matter into energy. 

Ordinary stars almost never emit 
many X rays. Another, more powerful 
mechanism is needed to generate that 
kind of high-energy radiation — grav- 
ity. When matter from an orbiting star 
falls toward a massive, compact object. 



such as a black hole whose mass is 
roughly the mass of a star, it doesn't 
fall directly onto the object's surface. 
Instead, the matter collects into a ro- 
tating disk of gas around the black 
hole, before it spirals downward into 
the hole, like water swirling into a 
bathtub drain. 

The disk of swirling gas releases 
gravitational potential energy as it falls 
inward. That energy is dispersed into 
rapid, random motions of the particles 
that make up the gas, superheating the 
falling gas. As its temperature rises to 
millions of degrees, the gas glows like 
the filament inside an incandescent 
lightbulb — except that, unlike the fil- 
ament, which emits visible light, the 
disk of gas emits mostly X rays. 

Plausible as it may sound, that 
mechanism still has trouble ac- 
counting for the torrent of X rays from 
ULXs. The puzzle arises because an 
object powered by the accretion of 
matter can theoretically emit energy 
only up to the so-called Eddington 
limit, named for the English astro- 
physicist Arthur Eddington, who first 
studied the problem. An object whose 
energy output exceeds this Umit would 
push away any infalling matter, cutting 
off the fuel supply that generates its lu- 
minosity in the first place. So its 
brightness, including its X-ray output, 
should top out at the Eddington Hmit. 
The Eddington limit for any object 
is directly proportional to its mass; 
for a black hole the mass of a few solar 
masses, it's about 50,000 times the 
luminosirv of the Sun. Imagine, then. 




Artist's conception of proposed mechanics of 
an ultraluminous X-ray source (ULXj. An inter- 
mediate-mass black hole (black dot at center 
of image) acts as a gravitational sink. Matter 
falls into the hole from the surrounding accre- 
tion disk, here exaggerated in size because of 
the angle of view. The star in the background 
supplies the matter that fuels the accretion 
disk at a rate of 10 trillion tons a second. 

the surprise in the 1980s when as- 
tronomers started to find X-ray 
sources with far greater luminosity 
than that. For such sources at the cen- 
ters of distant galaxies, the X-ray emis- 
sions could be explained only by the 
existence of a supermassive black hole, 
millions or billions of times the mass of 
the Sun [see "Peering at the Edge of 
Time," by Fuhno Meliojiiiie 2003]. But 
for objects on the outer fringes of 
galaxies — which presumably are star- 
size and not supermassive — these Ed- 
dington-busting ultraluminous sources 
have remained a mystery. 

Zampieri and his colleagues have 
joined the discussion on the side of a 
recently proposed hypothesis. Some 
ULXs, they maintain, are not stellar- 
mass objects that exceed the Edding- 
ton luminosity. They are bright be- 
cause they are much more massive 
than any typical star. Such a ULX 
would be powered by a black hole of 
intermediate size — perhaps a few 
hundred times the mass of the Sun, 
rather than millions or billions. The 
hypothetical model requires the com- 
panion star that supplies the infaUing 
matter to be nearby. 

Zampieri's group supports this 
model with their analysis of a ULX in 



64 NATURAL HISTORY May 2004 



the spiral galaxy NGC 1313. They 
combined data from the XMM-New- 
ton telescope with data from past X- 
ray telescope observations to measure 
the X-ray luminosity of the ULX. 
Then, with data from Chandra, they 
determined the precise position of the 
X-ray source and matched that posi- 
tion with visible-light observations. 
Thus they identified a star that corre- 
sponds to the position oi the ULX — 
thereby specifying the fuel source for 
the black hole. According to their cal- 
culations, the mass of the unseen black 



hole is between 100 and 700 times the 
mass of the Sun. 

That result, if it stands up to 
scrutiny, would be tremendously 
exciting — and not just to X-ray as- 
tronomers. Intermediate-mass black 
holes have long escaped detection, and 
definitively confirming the existence 
of even one would be a major advance. 
But interpreting these data is tricky. 
Just because a visible star corresponds 
with the telescopic position of an X- 
ray source doesn't inean the two ob- 



jects are truly associated. Nor can the 
observations rule out other proposed 
physical models for ULXs that do not 
require the presence of an intermedi- 
ate-mass black hole. The X rays, for 
instance, could be generated by fo- 
cused jets of matter shooting toward 
Earth, duping us into thinking the 
ULX is more luminous than it actually 
is. The jury on the real identity of the 
ULX, alas, is stiU out. 

Charles Liu is a professor of astrophysics at the 
City University of New York and an associate at 
the American Museum of Natural History. 



THE SKY IN MAY 

Mercury reaches its greatest western elongation, 
26 degrees from the Sun, on May 14. The planet 
nonetheless presents a crummy apparition this 
month for viewers at mid-northern latitudes, be- 
cause it rises less than an hour before the Sun. 
The farther south you are, the better your 
chances of seeing Mercury. 



Venus is the first "star" to appear at dusk, and by late twi- 
Hght it is truly dazzhng. On the 2nd Venus reaches its 
greatest brilliancy for this apparition: magnitude -4.5. 
The planet is so bright it can easily be seen with the 
naked eye in a deep-blue, haze-free afternoon sky. After 
nightfall at a very dark site, the planet's Hght can cast 
Venus-shadows. Venus begins the month more than 35 
degrees above the western horizon at sunset and doesn't 
set for another three hours; by month's end, though, it 
plummets to a sunset altitude of less than 10 degrees and 
sets only an hour later. This month is an exciting time to 
foUow Venus with a telescope; it's a beautiful crescent that 
grows bigger and (somewhat counterintuitively) thinner 
week after week. 

Dim Mars is low in the west-northwestern sky at dusk 
and sets in the northwest between 11 P.M. and 11:30 P.M. 
local dayhght time. 

After Venus, Jupiter is the brightest starlike object in the 
sky, shining this month high in the south-southwest at 
dusk. It overpowers the first-magnitude star Regulus, 9 
or 10 degrees to the planet's west. Examine the two after 
it gets dark enough to compare their colors: Regulus 
shines with a bluish hue, whereas Jupiter appears silvery 
white. The Moon can be found to the right of Jupiter 
on the 26th, and above and to the left of the planet the 
following night. 




By Joe Rao 

Saturn, in the constellation Gemini, starts the 
month well up in the northwestern sky at dusk, 
and sets just after midnight. By month's end, 
however, it sets by around 10:30 P.M. local day- 
light time. Mars, much dimmer than the ringed 
planet, passes less than 2 degrees north of Sat- 
urn on the evening of the 24th. 



The Moon waxes full on the 4th at 4:33 p.m. There is a 
total lunar eclipse that day, not visible from North Amer- 
ica, though part or all of the eclipse can be seen in 
Africa, Antarctica, most of Asia (including the Middle 
East), Europe, and South America. Our satellite wanes to 
last quarter on the 1 1th at 7:04 a.m. It becomes new on 
the 19th at 12:52 a.m. and waxes to first quarter on the 
27th at 3:57 a.m. 

In the first week of May, early risers might get a glimpse 
of Comet C/2002 T7 (LINEAR) just above the eastern hori- 
zon, about an hour before sunrise. Thereafter, the comet 
moves too far south for observers to see it fi'om the 
northern hemisphere. 

On the 5th, about an hour after sunset. Comet C/2001 
Q4 (NEAT) should be hovering about 10 degrees to the left 
of Sirius, in the constellation Canis Major. (Your clenched 
fist, held at arm's length, spans roughly 10 degrees.) Look 
low in the southwest for blue white Sirius, the dog star; it's 
the brightest star in the night sky. On the following nights 
the comet cUmbs progressively higher in the southwestern 
sky and becomes correspondingly easier to see. 

Both comets could reach fii-st magnimde or brighter. But 
both also seem to be making their first approach to the 
vicinity of the Sun, and past experience has showTi that "fii-st 
timers" usually fall far short of brightness expectations. 

Unless otherwise noted, all times are given in Eastern Daylight Time. 



t^ ay 2004 N.^TUR.^L HISTORY 65 



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At the Museum 

American Museum S Natural History ^ 

Museum Scientist Takes On Bugs 
of the Southern Hemisphere 



Leads team aiming to study 
5,000 species of plant-eating bugs 



/ 



The project's goal is to 
create a world taxonomy and 
database for these bugs that 
feed by sucking the juices from 
host plants. Because the bio- 
diversity of all life is generally 
better known in the Northern 
Hemisphere than in the South- 
ern, this project will focus on 
the tremendous plant and 
insect biodiversity concen- 
trated in the Southern Hemi- 
sphere, especially in Australia 
and South Africa. 

"Australia's insect 
biota is virtually un- 
known to many 
entomologists outside 
that country," said Dr. 
Schuh. "To understand 
the world's insect 
biota, you have to un- 
derstand Australia's in- 
sect biota. Prior to 1995, 
one might have 

concluded that 

feeds on manzanita. . ^ i- 1 j 

Australia had a 

very limited fauna. But with 
the collecting that Dr. Cassis 
and I have done in the past 
seven years, we are finally get- 
ting a decent representation 
of these creatures. Now, with 
this grant project, the broad 
outlines of the Australian and 
Southern Hemisphere biota 
overall will be well known." 

Dr. Cassis calls this project 
"the research opportunity of a 
lifetime," and believes it will 



Bugs "down under" will 
take center stage in a new 
collaborative five-year 
project between scientists at 
the American Museum of 
Natural History and colleagues 
at other prominent research 
institutions. Funded by the 
National Science Foundation 
(NSF), the $3 million initiative 
will involve collecting and 
compiling global biodiversity 
information on plant-feeding 
insects of the family 
Miridae, with a focus 
on the Australian 
and South African 
species of these / 
bugs. Randall T. 
Schuh, Curator and 
Chair of the Museum's 
Division of Invertebrate 
Zoology, is coleading the 
project with Gerry 
Cassis, head of 

the Centre for Aurantiocoris cuneotinctus 

Biodiversity and 
Conservation Research at 
the Australian Museum. 
Teams of entomologists led by 
Drs. Schuh and Cassis will 
oversee this multipronged 
effort together with Thomas ]. 
Henry of the U.S. Department 
of Agriculture's Systematic 
Entomology Laboratory and 
Michael D. Schwartz of Agri- 
culture and Agri-Food Canada, 
also leading specialists on 
these insects. 





Randall Schuh in Central Australia, October 2001 



make a spectacular contribu- 
tion to the international under- 
standing of biodiversity "The 
Miridae, a family of sap-suck- 
ing insects, is one of the most 
diverse groups of life on the 
planet," he says. "These 
bugs — some barely bigger 
than a pinhead — were here be- 
fore the dinosaurs, and have 
not only survived, but have 
flourished to the point where 
you find them everywhere." 

Insects are estimated to 
comprise 75 percent of Earth's 
biodiversity at the species 
level. Plant bugs, including 
the Miridae, represent a 
tremendous amount of that 
biodiversity. 

Data for the plant bugs pro- 
ject, which also involves sci- 



entists from Canada, Colom- 
bia, Germany, Russia, and the 
United States, will consist of 
about 550,000 specimens 
already in museums and 
another 100,000 speci- 
mens — mainly of the relatively 
unknown insect biota of 
Southern Hemisphere loca- 
tions like Australia, Chile, 
South Africa, and parts of 
Asia — to be acquired through 
15 to 20 field expeditions such 
as the 2002 Constantine S. 
Niarchos Expedition to Aus- 
tralia. The investigators plan 
to ramp up collection efforts 
extensively in these locations, 
as they have been poorly sam- 
pled in the past. 

All told, the specimens 
studied will represent more 



than 5,000 species with 
nearly 25 percent of them to 
be described as new. (For 
comparison, most individual 
taxonomists are lucky to 
describe 30 new species in 
a year.) About 800 of the 
species collected will come 
from Australia, where there is 
a high degree of insect en- 
demism, or insects that live 
only on this continent. The 
scientists also will note the 
species of plants on which 
each of the collected insects 
is found to create a database 
that indicates the host plants 
for each group of bugs. 

Drs. Schuh and Cassis are 
renowned experts on plant 
bugs and have collaborated 
for several years in collecting 
and studying them. With this 
grant, they can increase their 
description and analytic 
efforts to an "industrial" 
scale, involving more than a 
dozen entomologists. Analy- 
sis of family-group relations 
among the greatly expanded 
inventory of species resulting 
from this project will involve 
use of the Museum's cluster 
supercomputer to search for 
the simplest family tree to 
describe all these bug 
species' evolutionary transi- 
tions from the tree's base 
to its farthest reaches. The 
supercomputer, 
one of the fastest 
in the world, is 
used Museum- 
wide to analyze 
complex arrays of 
biological data 
and arrive at 
the best tree for- 
mation among 
many possible 
trees that could 
describe the 
evolutionary 
relationships 
among groups of 
species. 




Cerry Cassis and Christiane Weirauch in South Africa's 
Western Cape Province, October 2003 



On the plant side, the pro- 
ject will double the number of 
known bug hosts to about 



these insects will be helpful 
in making decisions about 
where conservation actions 



The project's goal is to create 
a world taxonomy and database 
for bugs that feed by sucking 
the juices from host plants. 




Gerry Cassis collecting 
plant bugs in South 
Africa's Western Cape 
Province, October 2003 



5,000, and boost the number 
of bug species with known 
hosts to more than 4,000. 
With this large body of infor- 
mation, theories of host 
association can be tested 

with the aim of 
understanding 
whether bugs 
have coevolved 
with their plant 
hosts, whether 
host affiliation is 
the result of eco- 
logical associa- 
tion, or whether 
the evolution of 
host associa- 
tions is driven 
by chemicals in 
plants. 

Improved 
knowledge of 




might best be directed. The 
project will also allow scien- 
tists to test theories 
about biodiversity 
hotspots and theo- 
ries of when insects 
radiated from place 
to place throughout 
Earth's history Both 
these areas of study are 
helpful to efforts to con- 
serve what remains of 
the world's insect biota. 

A major compo- ,- j 1 

' '^ Tuxedo elongatus 

nent of the research feeds on oaks. 

for the project will 
involve taxonomic and sys- 
tematic biology training of 
Ph.D. candidates and post- 
doctoral fellows, an element 
of particular importance 
given the global decline in 
taxonomists and natural 



resource managers even at a 
time of rapid commercial 
development. The project 
results will be distributed 
through a searchable Web site 
featuring images, a complete 
taxonomic catalog, interactive 
mapping of distributions, and 
interactive identification keys 
and will eventually be made 
available to the public via a 
traveling museum exhibition. 

The ambitious project 
brings many of the world's 
great natural history mu- 
seums together to 
solve global biodiver- 
sity problems. Collab- 
orators include the 
Smithsonian Institution, 
the Canadian National 
Insect Collection, and 
the Zoological Institute 
of the Russian Academy 
of Sciences, along with 
the American Mu- 
seum of Natural 
History and the 
Australian Museum. The 
grant for the project was 
made under the NSF's Plane- 
tary Biodiversity Inventory 
initiative, the objectives of 
which include documenting 
all Earth's species. 



The contents of these paces are provided to Natural History by the American Museum of Natural History. 



Museum Events 

American Museum S Natural History ^ 




Sea of Clouds 

EXHIBITIONS 

Exploratorium/AMNH 

Through August 15 
This exhibition invites visitors 
to explore fundamental 
concepts and phenomena in 
the natural sciences. Fun, 
hands-on displays clustered 
around four themes — Earth 
processes, rotation, mirrors 
and illusion, and pendulums — 
encourage audiences of all 
ages and all levels to 
investigate and play. 

Exploratorium/AM N H is funded in part by 
a grant from the Small Business Adminis- 
tration. For information on accessibility, 
call 212-769-5100. 

Petra: Lost City of Stone 

Through July 6 
This exhibition tells the story 
of a thriving metropolis at the 
crossroads of the ancient 
world's major trade routes. 

In New York, Petra: Lost City of Stone 
is made possible by Banc of America 
Securities and Con Edison. The American 
Museum of Natural History also gratefully 
acknowledges the generous support of 
Lionel I. Pincus and HRH Princess Firyal 
and of The Andrew W. Mellon Foundation. 
This exhibition is organized by the 
American Museum of Natural History, 
New York, and the Cincinnati Art Museum, 
under the patronage of Her Majesty 
Queen Rania Al-Abdullah of the Hashemite 
Kingdom of Jordan. Air transportation 
generously provided by Royal Jordanian. 



The Bedouin of Petra 

Through July 6 

Photojournalist Vivian Ronay's 
evocative color photographs 
document the Bedoul group 
of Bedouin tribes living near 
the archaeological site of 
Petra in Jordan. 

This exhibition is made possible by the 
generosity of the Arthur Ross Foundation. 

The Butterfly Conservatory: 
Tropical Butterflies Alive 
in Winter 

Through May ji 




Last chance for butterflies! 
This popular exhibition 
includes more than 500 live, 
free-flying tropical butterflies 
in an enclosed tropical habitat 
w/here visitors can mingle 
with them. 

The Butteffly Conservatory is made 
possible through the generous support 
of Bernard and Anne Spitzer. 



Seasons of Life and Land: 
Arctic National Wildlife Refuge 

Through September 6 
Stunning large-format color 
photographs by conservationist 
Subhankar Banerjee focus on 
the interdependence of land, 
water, wildlife, and humanity 
in Alaska's Arctic Refuge. 

Art for Heart 

Through September 26 
Paintings by children who lost 
loved ones in the attacks on 
New York City's World Trade 
Center on February 26, 1993, 
and September 11, 2001, 
create a powerful and 
poignant memorial. 

Made possible by the Lower Manhattan 
Development Corporation. 

LECTURES 

Adventures in the Global 

Kitchen 

Tuesday, ^/4, y:oo p.m. 
Culinary collaboration 
between Museum entomolo- 
gist Lou Sorkin, Citarella's 
celebrated pastry chef Bill 
Yosses, and Gene Rurka of 
the Explorers Club. 



The Beast in the Garden 

Tliursday, 5/23, 7:00 p.m. 
David Baron's new book 
considers implications 
of wildlife protection laws: 
can humans learn to coexist 
with large predators that 
have been brought back 
to abundance? 

Art/Sci Collision: 
An Evening with 
Ned Kahn 

Tuesday, ^/i8, y:oo p.m. 
At the intersection of science 
and art, Ned Kahn's work 
draws from a palette of 
natural phenomena. 




FIELD TRIP 

Around Manhattan Island 

Thursday, ^/2^, 6:00 p.m. 
A three-hour cruise with 
geologist Sidney Horenstein. 



Starry Nights 




Live Jazz 






Friday, May 7 


^^^MH 


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5:30 and 7:00 p.m. 
Rose Center for Earth 


^^^ 


|HI 




and Space 


^B^S 






Houston Person Quartet 


^B_? 


^mj^M 




starry Nights is made possible by 
Lead Sponsor Verizon and 
Associate Sponsors CenterCare 
Health Plan, Constellation 
NewEnergy, and WNBC-TV. 


H 


1 













"-■•^*'" 



FAMILY AND 
CHILDREN'S PROGRAMS 
Oceanophony 

Saturday, 5/1, 1:00-2:00 p.m. 
or y.oo-4:oo p.m. 
Join Bruce Adolphe and his 
PollyRhythm Players for a 
weird and wonderful musical 
voyage to the mysterious deep. 

Earthly Adventures 

Sunday, ^/i, 12:^0-2:00 p.m. 
{Ages 4-5, each child with 
one adult) or ^00-4:^0 p.m. 
(Ages 6-7) 

Explore earthquakes, torna- 
does, and other forces of 
nature in this hands-on 
workshop. 

Space Explorers: 
Transit of Venus 

Tuesday, j/n, 4:^0-^4^ p.m. 
(Ages 10 and up) 
On the second Tuesday of 
each month, kids can learn 
under the stars of the Hayden 
Planetarium Space Theater. 

I Want to Be an Astronaut 

Sunday, ^/i6 

12:^0-2:00 p.m. (Ages 4-^, 
each child with one adult) 
or y.oo-4:}o p.m. (Ages 6-y) 
Three, two, one, blast off! 
Find out what life is like 250 
miles above Earth on the 
International Space Station. 



INFORMATION 

Call 212-769-5100 or visit 
www.amnh.org. 

TICKETS AND 
REGISTRATION 

Call 212-769-5200, 
Monday-Friday, 
9:00 a.m. -5:00 p.m., 
or visit www.amnh.org. 
A service charge may apply 

All programs are subject to 
change. 



Julie of the Wolves 

Sunday, ^/i6, 2:00 p.m. 
A musical adaptation of 
the children's classic about 
a young Eskimo girl who 
runs away and is protected 
by wolves. 

Red Rover to Mars 

Tuesday-Thursday, 5/18-20 
4:00-^^0 p.m. (Ages 12-1^) 
Students learn about the his- 
tory of NASA's rovers and 
what we learn from them, and 
then design and build their 
very own "rovers." 




The vehicle carrying the Mars rover 
Opportunity poised for launch 

HAYDEN PLANETARIUM 
PROGRAMS 

TUESDAYS IN THE DOME 
Virtual Universe: 
The Big Bang and 
Cosmic Construction 

Tuesday, ^/4 
6:]o-'/:}o p.m. 

This Just In. . . 
May's Hot Topics 

Tuesday, ^/i8 
6:jo-7:]o p.m. 

Celestial Highlights: 
Transit of Venus 

Tuesday, ^/2^ 
6:^o-y:^o p.m. 



COURSE 

Eclipses and Transits 

Four Mondays, ^1^-24 
6:^0-^:^0 p.m. 

Explore the mechanics behind 
impressive celestial phenom- 
ena, and prepare for the much- 
anticipated transit of Venus. 

LECTURES 

Life, the Universe, 

and SETI in a Nutshell 

Monday, ^/j, 7:^0 p.m. 
SETI's Jill Tarter leads this 
discussion on the future of 
our search for life elsewhere 
in the universe. 

The Book Nobody Read 

Monday, ^/lo, j:}0 p.m. 
Astronomer Owen Gingerich's 
new bibliographic detective 
story revisits Copernicus's 
De Revolutionihus, which first 
proposed that Earth 
revolved around the Sun. 

PLANETARIUM SHOWS 

SonicYision 

Fridays and Saturdays, 'j:}o, 
&:;}o, g:]o, and 10:^0 p.m. 
A mind-warping musical and 
visual roller-coaster ride. 

SonicVislon is made possible by generous 
sponsorship and technology support 
from Sun Microsystems, Inc. 



The Search for Life: 
Are We Alone? 

Narrated by Harrison Ford 

Made possible through the generous 
support of Swiss Re. 

Passport to the Universe 

Narrated by Tom Hanks 

LARGE-FORMAT FILMS 

LeFrak Theater 

Bugs'. 

This live-action rain forest 

adventure follows the 




dramatic lives of a praying 
mantis and a graceful 
butterfly and ends with their 
inevitable encounter. 

Volcanoes of the Deep Sea 

Explore Earth's most hostile 
environments and its strangest 
creatures, and consider the 
implications for our search 
for life. 



Become a Member of tlie 
American Museum of Natural History 

As a Museum Member you will be among the first to 

embark on new journeys to explore the natural world 

and the cultures of humanity. You'll enjoy: 



' Unlimited free general 
admission to the Museum 
and special exhibitions, and 
discounts on Space Shows 
and IMAX® films 

' Discounts in the Museum 
Shop, restaurants, and on 
program tickets 



• Free subscription 
to Natural History 
magazine and to Rotunda, 
our newsletter 

• Invitations to Members- 
only special events, 
parties, and exhibition 
previews 



For further information, call 212-769-5606 
or visit www.amnh.org. 



The comtents or these pages are provided to Natural History by the American Museum of Natural History. 



ENDPAPER 



The Face 
of Extinction 



By Hanna Rose Shel 



Until the middle of the nineteenth century, 
as documented by no less an eininence 
than John James Audubon, passenger pi- 
geons by the biUions turned day to night as they 
passed overhead in the American skies [see "Audubon 
ill Kentucky," by Williani Sender, page 46]. Yet by the 
turn of the twentieth century, all that had changed: 
fifty years of relentless extennination forever ban- 
ished Ectopistes niigmtoriiis from the Earth. The last 
passenger pigeon in the wild was reportedly shot by 
a boy in Ohio in 1900. 

But the species officially went extinct only with 
the death of Martha, a denizen of the Cincinnati 
Zoo. Martha had been born in about 1894, and, in 
her youth, she had a female passenger pigeon's 
classic good looks: pale cinnamon-rose breast; long, 
pointed tail feathers; a graceful head and neck. By 
the year of her death, the news of an incipient ex- 
tinction, together with clamorous announcements 
of unclaimed cash rewards for locating a passenger 
pigeon nest or colony, was attracting visitors from 
far and wide to Martha's red-roofed aviary in Ohio. 
In the following years, many more visitors turned 
out to admire Martha's taxidermied mount in the 
Birds of Our World gallery, at the National Museum 
ot Natural History in Washington, D.C. Martha's 
presentation there, in fact, was carefuUy planned. 
Her body had been proinised to the Smithsonian, 
and when she finally expired, in September 1914, 
the zookeepers rushed her corpse to the Cincinnati 
Ice Company. There, held by her feet, she was low- 
ered into a tank of water, frozen upside down in a 
300-pound block of ice, and shipped by express train 
to the capital. 

Martha was officially signed into the Smithsonian 
collections as a "passenger pigeon in the flesh." Her 
accession card is by turns blunt, then sentimental: 
"The death of this individual marks the complete 
extinction of the genus and species, of the countless 
hordes ot other days." She was unpacked, thawed, 
and autopsied. Several organs — including her eyes. 




Martha in death: the last passenger pigeon 

brain, and Hver — were examined and placed in sep- 
arate jars of ethyl alcohol. 

Once Martha's taxidermic treatment was com- 
plete, she was perched on a model "branch," 
enclosed in a glass case, and given a post of proini- 
nence in the gallery, surrounded by other extinct and 
endangered avians from North America. In her new, 
postmortem role, she even went on the road several 
times on behalf of species that were facing the threat 
of extinction. She served as a tabletop mascot at a 
conservation conference for the San Diego Zoo at 
the zoo's golden jubilee, in 1966, and at a Cincinnati 
Zoo fund-raiser, in 1974. She always flew first class, 
coddled by the flight crew and protected, at least fi- 
nancially, by a hefty insurance pohcy. 

Almost five years ago, though, around the turn of 
the millennium, Martha's perch went dark. The 
Smithsonian Institution closed its bird gallery indef- 
initely to the public at the end of 1999. And now 
the last exemplar of a vanished species is hidden 
away in a storage cabinet in the bird division's re- 
search collections. 

Yet without reminders such as Martha, how are 
people to visualize, materialize, and memorialize 
the Earth's destroyed and extinguished species? 
After eighty-five years in the pubUc eye, the figure 
of Martha has become an organic monument, bio- 
logically continuous with the living bird she com- 
memorates, the embodiment of extinction itself. 
In the words of the naturalist Aldo Leopold, effigies 
such as Martha's "live forever by not living at all." 

Hanna Rose Shell is a liistorian of science at Harvard Uni- 
versity and a fihnmaker She recently edited the new edition of 
William T. Hornaday's 1889 hook, Extermination of the 
American Bison (Smithsonian Institution Press, 2002). 



72 NATURAL HISTORY t^ ay 2004 



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